Humulin R is a brand-name medication that’s available both over the counter and by prescription. It’s used to help manage blood sugar levels in adults and children with either type 1 or type 2 diabetes.

Humulin R comes as a liquid solution. It’s given as an injection under your skin (called a subcutaneous injection). You’ll give the injections to yourself once your doctor has shown you how to administer the medication.

Humulin R is available in two strengths:

  • Humulin R U-100. This strength contains 100 units of insulin per 1 milliliter (mL) of solution. It comes in 3-mL and 10-mL vials.*
  • Humulin R U-500. This strength contains 500 units of insulin per 1 mL of solution. It comes in a 20-mL vial.* It’s also available as a 3-mL KwikPen,** which is a prefilled pen that’s meant to be used by only one person.

* If you’re using vials of Humulin R, you’ll need to purchase appropriate syringes and needles to administer the drug.
** If you’re using the Humulin R KwikPen, you’ll need to purchase appropriate needles to use with the pen.

Form of insulin in Humulin R

Humulin R contains the active drug insulin human. It belongs to a class of medications called short-acting insulins. (A medication class is a group of medications that work in a similar way). Humulin R is typically given two to three times each day before meals.

Insulin human is a “recombinant” insulin. This means it’s made in a lab using special DNA technology that combines genetic material in order to make the insulin. This process allows the drug manufacturer to create an exact copy of the insulin that your body makes naturally.

Effectiveness of Humulin R

In clinical trials, Humulin R was effective in improving blood sugar levels in people with either type 1 or type 2 diabetes. For information about the drug’s effectiveness, see the “Humulin R for diabetes” section below.

Humulin R is available only as a brand-name medication. It’s not currently available in generic form. A generic drug is an exact copy of the active drug in a brand-name medication.

Humulin R contains the active drug insulin human. The American Diabetes Association (ADA) also refers to this drug as “regular insulin,” “human insulin,” and “human regular insulin.” But no matter which name is used, they’re all referring to the same drug.

There is a drug available, called Novolin R, that’s similar to Humulin R. It contains the drug human insulin. For more information about this drug, see the section “Humulin R vs. Novolin R” below.

The Humulin R dosage your doctor prescribes will depend on several factors. These include:

  • the type and severity of the condition you’re using Humulin R to treat
  • your age
  • the form of Humulin R you’re taking
  • other medical conditions you may have

Typically, your doctor will start you on a low dosage. Then they’ll adjust it over time to reach the amount that’s right for you. Your doctor will ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Note: Making changes to your insulin treatment plan without consulting your doctor could increase your risk for both hypoglycemia (low blood sugar levels) and hyperglycemia (high blood sugar levels). These changes may include administering your insulin differently than you usually do or injecting the drug into areas of skin that are thickened or pitted. They could also include taking a new dosage of insulin or using a new insulin product.

If your doctor changes your Humulin R dosage, they’ll likely have you monitor your blood sugar levels more often than usual. This allows you to monitor for high and low blood sugar levels.

Drug forms and strengths

Humulin R comes as a liquid solution. It’s available in two strengths:

  • Humulin R U-100. This strength contains 100 units of insulin per 1 mL of solution. It comes in 3-mL and 10-mL vials.* In the 3-mL vial, you’ll have a total of 300 units of insulin human. And in the 10-mL vial, you’ll have a total of 1,000 units of insulin human.
  • Humulin R U-500. This strength contains 500 units of insulin per 1 mL of solution. It comes in a 20-mL vial.* It’s also available as a 3-mL KwikPen,** which is a prefilled pen that’s meant to be used only by one person. In the 20-mL vial, you’ll have a total of 10,000 units of insulin human. And in the 3-mL KwikPen, you’ll have a total of 1,500 units of insulin human.

Both the vials of Humulin R and the KwikPens are meant to be used more than once. However, the actual number of times you’ll use a certain vial or pen will depend on your insulin dosage.

But keep in mind that you’ll need to use a new syringe and a new needle for each dose of Humulin R from a vial. And you’ll need to use a new needle for each dose of insulin from a KwikPen. Using needles or syringes more than once can increase your risk of infection.

Humulin R is given as an injection under your skin (called a subcutaneous injection). You’ll give the injections to yourself once your doctor has shown you how to administer the drug.

* If you’re using vials of Humulin R, you’ll need to purchase appropriate syringes and needles to administer the drug.
** If you’re using the Humulin R KwikPen, you’ll need to purchase appropriate needles to use with the pen.

Dosage for diabetes

Usual dosages of Humulin R for both type 1 and type 2 diabetes are described below. However, your doctor will recommend a specific dosage that’s right for you.

If you have either type 1 or type 2 diabetes, your doctor will determine your insulin dosage based on your blood sugar levels and your blood sugar level goals.

For type 1 diabetes

The package information for Humulin R doesn’t contain exact dosage guidance for type 1 diabetes. But the American Diabetes Association (ADA) provides the following recommendations.

A typical starting dosage for type 1 diabetes is about 0.5 units of Humulin R per kilogram of your body weight per day (1 kilogram is equal to about 2.2 pounds). This daily dosage is split into two or three injections, which are each given about 30 minutes before your meals.

For type 2 diabetes

The package information for Humulin R doesn’t contain exact dosage guidance for type 2 diabetes. But the ADA provides the following recommendations.

A typical starting dosage for type 2 diabetes is around 0.1 to 0.2 units of Humulin R per kilogram of your body weight per day. (One kilogram is equal to about 2.2 pounds.) This daily dosage is split into two or three injections, which are each given about 30 minutes before your meals.

Sliding scale dosage

It’s also possible to use sliding scale dosing for Humulin R. When using a sliding scale, your doctor works with you to create a chart of insulin doses. The doses vary based on how your body responds to insulin and how physically active you are. The doses also vary depending on the amount of carbohydrates you consume in an average day.

To figure out your insulin dose, you first test your blood sugar level. You then find the matching blood sugar level on your sliding scale chart. Next, you match up that blood sugar level with the corresponding insulin dose on the chart.

If you have questions about using a slide scale, talk with your doctor.

Pediatric dosage

The manufacturer of Humulin R hasn’t given specific dosage recommendations for children using the drug. Instead, your child’s doctor will recommend a starting dosage. They may use the same dosing guidelines used for adults taking this drug. See the section above called “Dosage for diabetes” for more information.

What if I miss a dose?

If you miss a dose of Humulin R, take it as soon as you remember. But if it’s nearly time for your next dose, just skip the missed dose and wait until your next scheduled dose. Don’t take more than one dose of Humulin R at a time. Doing so can increase your risk for serious side effects, such as hypoglycemia (low blood sugar level).

To help make sure that you don’t miss a dose, try setting a reminder on your phone. A medication timer may be useful, too.

Will I need to use this drug long term?

Humulin R is meant to be used as a long-term treatment. If you and your doctor determine that Humulin R is safe and effective for you, you’ll likely take it long term.

In addition to Humulin R, other medications are available that can be used to treat diabetes. Some may be a better fit for you than others. If you’re interested in finding an alternative to Humulin R, talk with your doctor. They can tell you about other medications that may work well for you.

Alternative insulins for either type 1 or type 2 diabetes

People with type 1 diabetes need to take insulin because their body can’t make its own insulin. And sometimes, people with type 2 diabetes also need to take insulin. This may be because their body has stopped making its own insulin or because other diabetes drugs aren’t working well enough.

Examples of insulins, other than Humulin R, that may be used to help manage blood sugar levels in people with either type 1 or type 2 diabetes include:

  • other short-acting insulins, which help you manage blood sugar level for about 3 to 6 hours, such as:
    • insulin human (Novolin R)
  • rapid-acting insulins, which start working within 15 minutes, and help manage blood your sugar level for about 2 to 4 hours, such as:
    • insulin aspart (NovoLog, Fiasp)
    • insulin glulisine (Apidra)
  • intermediate-acting insulins, which help manage your blood sugar level for about 12 to 18 hours, such as:
    • insulin NPH (Humulin N, Novolin N)
  • long-acting insulins, which help manage your blood sugar level for 24 hours or longer, such as:
    • insulin degludec (Tresiba)

Alternative drugs other than insulin for type 2 diabetes

There are several drugs other than insulin that are used to help manage blood sugar levels in people with type 2 diabetes. Examples of these drugs include:

  • biguanides, such as metformin
  • dipeptidyl peptidase-4 (DPP-4) inhibitors, such as:
    • alogliptin (Nesina)
    • linagliptin (Tradjenta)
    • saxagliptin (Onglyza)
  • glucagon-like peptide 1 (GLP-1) agonists, such as:
    • lixisenatide (Adlyxin)
  • sodium-glucose co-transporter 2 (SGLT2) inhibitors, such as:
    • ertugliflozin (Steglatro)
  • sulfonylureas, such as:
    • glimepiride (Amaryl)
    • glipizide (Glucotrol)
  • thiazolidinediones (TZDs), such as:
    • pioglitazone (Actos)
    • rosiglitazone (Avandia)

You may wonder how Humulin R compares with other medications that are prescribed for similar uses. Here we look at how Humulin R and Novolin R are alike and different.

Ingredients

Humulin R contains the drug insulin human. Novolin R contains the drug human insulin, which is also sometimes called insulin human.

Like Humulin R, Novolin R is also made in a lab using recombinant DNA technology. (With this technology, genetic material is combined and used to make the insulin.)

However, Novolin R is made by a different manufacturer than Humulin R is. And it’s not an exact copy of Humulin R. This is because the way the drugs are made is very complex, and an exact copy of the original drug can’t be made.

But both drugs contain identical copies of the insulin your body makes naturally. And both drugs belong to the same class of drugs called short-acting insulins. (A medication class is a group of medications that work in a similar way.) Short-acting insulins help manage your blood sugar level for about 3 to 6 hours.

Uses

Humulin R and Novolin R are both approved to manage blood sugar levels. These drugs can be used by adults and children with either type 1 or type 2 diabetes.

Drug forms and administration

Humulin R comes as a liquid solution. It’s available in two strengths:

  • Humulin R U-100. This strength contains 100 units of insulin per 1 mL of solution. It comes in 3-mL and 10-mL vials. In the 3-mL vial, you’ll have a total of 300 units of insulin human. And in the 10-mL vial, you’ll have a total of 1,000 units of insulin human.
  • Humulin R U-500. This strength contains 500 units of insulin per 1 mL of solution. It comes in a 20-mL vial. It’s also available as a 3-mL KwikPen, which is a prefilled pen that’s meant to be used more than once, but only by one person. In the 20-mL vial, you’ll have a total of 10,000 units of insulin human. And in the 3-mL KwikPen, you’ll have a total of 1,500 units of insulin human.

Novolin R also comes as a liquid solution. It’s available in one strength, U-100, which comes in the following products:

  • 10-mL vials, which each hold a total of 1,000 units of insulin human
  • FlexPens, which are 3-mL prefilled pens that are meant to be used more than once, but only by one person; each pen holds a total of 300 units of insulin human

Whether you’re using vials of either Humulin R or Novolin R, you’ll need to purchase appropriate syringes and needles to administer the drug. And you should use a new needle and a new syringe for each dose.

And if you’re using either the KwikPen or the FlexPen, you’ll need to purchase appropriate needles to use with the pen. You should use a new needle for each dose of insulin given with the pen.

Both Humulin R and Novolin R are given as an injection under your skin (called a subcutaneous injection). You’ll give the injections to yourself once your doctor has shown you how to administer the drug.

In some cases, Humulin R and Novolin R are given as an intravenous (IV) infusions by healthcare providers. (With an IV infusion, the drug is injected into your vein over a period of time.)

Side effects and risks

Humulin R and Novolin R both contain insulin human. Therefore, these medications cause very similar side effects. For more information about the possible side effects of Humulin R, see the section “Humulin R side effects” below.

Effectiveness

These drugs haven’t been directly compared in clinical studies. But separate studies have found both Humulin R and Novolin R to be effective in managing blood sugar levels in adults and children with either type 1 or type 2 diabetes.

Costs

Humulin R and Novolin R are both brand-name drugs. There are currently no generic forms available of either drug.

Humulin R and Novolin R are also each available in over-the-counter (OTC) forms. The cost of each OTC drug will be different from the cost of each prescription drug. However, it’s important to talk with your doctor before switching from prescription to OTC insulin. Your doctor will recommend the safest way for you to make this switch.

Novolin R is also available under the ReliOn brand, which is only available at Wal-Mart stores. The ReliOn form of Novolin R generally costs less than brand-name Novolin R costs.

According to estimates on GoodRx.com, Humulin R costs significantly more than Novolin R. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Like Novolin R (described above), Humulin N is another option that’s prescribed for similar uses. Here we look at how Humulin R and Humulin N are alike and different.

Ingredients

Both Humulin R and Humulin N contain the active drug insulin human.

However, Humulin N contains a modified form of insulin human that’s combined with a protein called protamine. Combining insulin human with protamine helps the drug to work in your body for a longer period of time than the insulin human in Humulin R does.

While both Humulin R and Humulin N are forms of regular human insulin, they each belong to a slightly different medication class. (A medication class is a group of medications that work in a similar way.)

Humulin R belongs to a class of medications called short-acting insulins, while Humulin N belongs to a class of medications called intermediate-acting insulins. Short-acting insulins help manage your blood sugar level for about 3 to 6 hours. On the other hand, intermediate-acting insulins help manage your blood sugar level for about 12 to 18 hours.

Uses

Humulin R and Humulin N are both approved to manage blood sugar levels in adults and children with either type 1 or type 2 diabetes.

Drug forms and administration

Humulin R comes as a liquid solution. It’s available in two strengths:

  • Humulin R U-100. This strength contains 100 units of insulin per 1 mL of solution. It comes in 3-mL and 10-mL vials. In the 3-mL vial, you’ll have a total of 300 units of insulin human. And in the 10-mL vial, you’ll have a total of 1,000 units of insulin human.
  • Humulin R U-500. This strength contains 500 units of insulin per 1 mL of solution. It comes in a 20-mL vial. It’s also available as a 3-mL KwikPen, which is a prefilled pen that’s meant to be used more than once, but only by one person. In the 20-mL vial, you’ll have a total of 10,000 units of insulin human. And in the 3-mL KwikPen, you’ll have a total of 1,500 units of insulin human.

Humulin N also comes as a liquid solution. It’s available in one strength, U-100, which comes in the following products:

  • 3-mL vials, which each hold a total of 300 units of human insulin
  • 10-mL vials, which each hold a total of 1,000 units of human insulin
  • KwikPens, which are 3-mL prefilled pens that are meant to be used more than once, but only by one person; each pen holds a total of 300 units of insulin human

Whether you’re using vials of either Humulin R or Humulin N, you’ll need to purchase appropriate syringes and needles to administer the drug. And you should use a new needle and a new syringe for each dose.

If you’re using the KwikPen, you’ll need to purchase appropriate needles to use with the pen. And you should use a new needle for each dose of insulin given with the pen.

Both Humulin R and Humulin N are given as an injection under your skin (called a subcutaneous injection). You’ll give the injections to yourself once your doctor has shown you how to administer the drug.

Side effects and risks

Humulin R and Humulin N both contain insulin human. Therefore, these medications can cause very similar side effects. Below are examples of these side effects.

Mild side effects

This list contains examples of mild side effects that can occur with both Humulin R and Humulin N, when they’re taken individually.

  • bloating
  • fluid retention (swelling), especially in your arms and legs
  • weight gain
  • injection site reaction, which may cause swelling and pain in the area where you inject either drug
  • protein buildup underneath your skin in the area where you inject either drug
  • skin lesions at the site of your injection (also called lipodystrophy)

Serious side effects

This list contains examples of serious side effects that can occur with both Humulin R and Humulin N, when they’re taken individually.

Effectiveness

These drugs haven’t been directly compared in clinical studies. But separate studies have found both Humulin R and Humulin N to be effective for managing blood sugar levels in adults and children with either type 1 or type 2 diabetes.

Costs

Humulin R and Humulin N are both brand-name drugs. There are currently no generic forms available of either drug.

Humulin R and Humulin N are also each available in over-the-counter (OTC) forms. The cost of each OTC drug will be different from the cost of each prescription drug. However, it’s important to talk with your doctor before switching from prescription to OTC insulin. Your doctor will recommend the safest way for you to make this switch.

According to estimates on GoodRx.com, Humulin R and Humulin N generally cost about the same. The actual price you’ll pay for either drug depends on your insurance plan, your location, and the pharmacy you use.

Humulin R is a form of insulin that’s approved to manage blood sugar levels in adults and children with either type 1 or type 2 diabetes.

How insulin affects blood sugar

Normally, after you eat food, it gets broken down in your stomach. And glucose (sugar) from the food travels into your bloodstream. In response to this, your body releases insulin.

Insulin is a hormone that helps move glucose out of your bloodstream and into your body’s cells. Once inside your cells, the glucose can be turned into energy.

Insulin is usually made by your pancreas. But in people with type 1 diabetes, their pancreas isn’t able to make insulin. And in people with type 2 diabetes, their body may still be making insulin, but their cells are resistant to the hormone. (With insulin resistance, your body stops responding to insulin the way it normally should.) Over time, it’s possible that people with type 2 diabetes might not be able to make their own insulin.

If your body is either not making insulin or not responding to it, your blood sugar level can get too high. (A high blood sugar level is called hyperglycemia.) Having high blood sugar levels can damage your organs. And with high blood sugar levels, your cells might not be getting the glucose they need for energy.

What Humulin R does

The active drug in Humulin R, called insulin human, is a copy of the insulin that’s naturally made by your pancreas. This drug is made using recombinant DNA technology. (With this technology, genetic material is combined in order to make the insulin.) Because Humulin R is a copy of natural insulin, your body uses the drug the exact same way it uses natural insulin.

Insulin human works by moving glucose out of your bloodstream and into your cells. This lowers your blood sugar level.

How long does it take to work?

Humulin R has an onset of about 30 minutes. (The term “onset” describes when a drug begins working in your body.) This means it takes Humulin R around 30 minutes to start working after you inject your dose.

Humulin R peak effect

Humulin R reaches its peak (highest) effect in your body around 3 hours after you inject the drug.

Humulin R duration

Humulin R has a duration of action of about 8 hours. (The term “duration of action” describes how long a drug continues working in your body after you take it.) This means that Humulin R keeps working in your body for a total of about 8 hours after you inject your dose. However, Humulin R works most effectively for about 3 to 6 hours after you take it.

Humulin R can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Humulin R. These lists do not include all possible side effects.

For more information on the possible side effects of Humulin R, talk with your doctor or pharmacist. They can give you tips on how to deal with any side effects that may be bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs they have approved. If you would like to report to the FDA a side effect you’ve had with Humulin R, you can do so through MedWatch.

Mild side effects

The mild side effects of Humulin R can include:

  • bloating
  • fluid retention (swelling), especially in your arms and legs
  • weight gain
  • injection site reactions, which may cause swelling and pain in the area where you inject the drug
  • protein buildup underneath your skin at the area where you inject the drug
  • skin lesions at the site of your injection (also called lipodystrophy)

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

Serious side effects

Serious side effects from Humulin R aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

* For more information about this side effect, see the “Side effect details” section just below.

Side effect details

You may wonder how often certain side effects occur with this drug. Here’s some detail on several of the side effects this drug may cause.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Humulin R. Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (warmth and redness in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have a severe allergic reaction to Humulin R. Call 911 if your symptoms feel life threatening or if you think you’re having a medical emergency.

Weight gain

Weight gain is a common side effect of all insulin products, including Humulin R.

In one clinical study, people with type 2 diabetes who started insulin therapy gained an average of about 4 pounds in their first year of treatment.

Because of how insulin works, this isn’t an unexpected side effect of the drug. Insulin helps your body to move sugar out of your bloodstream and into your cells. Once inside your cells, the sugar is turned into energy. But if the sugar isn’t needed right away for energy, your cells will store it for later use. Excessive sugar is stored as body fat.

Weight gain is also a common symptom in people with diabetes. In fact, people with type 1 diabetes are at higher risk for having excess body weight or obesity than are people who don’t have diabetes.

If you’re concerned about gaining weight while you’re using Humulin R, talk with your doctor. They can help you manage a body weight that’s healthy for you.

Hypoglycemia

You may have hypoglycemia (low blood sugar level) while you’re taking Humulin R. In fact, it’s the most common side effect of the drug.

In one clinical study, 92% of people switching from Humulin R U-100 to Humulin R U-500 had some level of hypoglycemia. There weren’t any people in this study taking a placebo (treatment with no active drug).

Talk with your doctor about how often you should check your blood sugar level. Monitoring this level can help prevent hypoglycemia while you and your doctor learn how your body responds to Humulin R.

While it’s important to use insulin to keep your blood sugar from getting too high, having low blood sugar can also be dangerous. Severe hypoglycemia can lead to seizures and even death in some cases.

Certain things can increase your risk of hypoglycemia, such as taking high doses of insulin or using more than one diabetes medication at time. Taking certain other medications that aren’t used for diabetes can also increase the risk of hypoglycemia. Other factors that may increase your risk of hypoglycemia include your diet and exercise habits.

Symptoms of hypoglycemia can include:

  • confusion
  • drowsiness
  • fatigue (lack of energy)
  • hunger
  • feeling irritable or anxious
  • being shaky

Symptoms of hypoglycemia can occur suddenly. And they can quickly become serious if not treated. Be sure to talk with your doctor about monitoring for hypoglycemia while you’re taking Humulin R. And also talk with them about what you should do if you’re having hypoglycemia.

Note: Making changes to your insulin treatment plan without consulting your doctor could increase your risk for both hypoglycemia and hyperglycemia (high blood sugar levels). These changes may include administering your insulin differently than you usually do or injecting the drug into areas of skin that are thickened or pitted. They could also include taking a new dosage of insulin or using a new insulin product.

Lipodystrophy

You may experience lipodystrophy while you’re taking Humulin R. Lipodystrophy is a depression in your skin or a thickening of your skin.

Humulin R is given by subcutaneous injection (an injection under your skin). Repeatedly giving subcutaneous injections in the same spots may cause lipodystrophy at or around your injection sites. For this reason, you should alternate the sites where you inject Humulin R. For example, if you inject the drug into your belly one day, you could inject into your thigh or upper arm the next day.

If you’re concerned about developing lipodystrophy while using Humulin R, talk with your doctor. They can recommend ways to help lower your risk of skin effects while you’re using this drug.

Injection site reactions

It’s possible to have injection site reactions at the site where you inject Humulin R. Examples of symptoms that may occur with injection site reactions include:

  • itchiness
  • pain
  • redness or swelling
  • skin discoloration
  • warmth

You shouldn’t inject Humulin R into an area of your skin that is itchy, red, or swollen. Doing so may increase your risk of a serious reaction, such as bleeding or hematoma (a collection of blood underneath your skin).

If you’re concerned about having injection site reactions while you’re taking Humulin R, talk with your doctor. They can discuss ways to minimize this side effect. And if you have injection site reactions that are bothersome, your doctor may switch you to a different diabetes drug.

When you get Humulin R from the pharmacy, the pharmacist will add an expiration date to the label on either the box of insulin pens or vials of insulin. This date is typically 1 year from the date they dispensed the medication.

The expiration date helps guarantee that the medication is effective during this time. The current stance of the Food and Drug Administration (FDA) is to avoid using expired medications. If you have unused medication that has gone past the expiration date, talk to your pharmacist about whether you might still be able to use it.

Storage

How long a medication remains good can depend on many factors, including how and where you store the medication.

But regardless of where it’s stored, be sure to protect Humulin R from heat and light. Also, avoid freezing Humulin R.

Storing Humulin R before opening

Unopened Humulin R vials should be stored in the refrigerator at a temperature between 36oF and 46oF (2oC to 8oC).

You may also wonder how long Humulin R can be kept unrefrigerated. The following list describes how long Humulin R can be kept at room temperature. But keep in mind that the room’s temperature should be below 86oF (30oC). When storing at room temperature:

  • unopened Humulin R U-100 vials can be kept for up to 31 days
  • unopened Humulin R U-500 vials can be kept for up to 40 days
  • unopened Humulin R U-500 KwikPens can be kept for up to 28 days

Storing Humulin R after opening

After opening, Humulin R U-100 vials can be stored either in the refrigerator (36oF to 46oF/2oC to 8oC) or at room temperature (below 86oF/30oC). The vials can be kept at either temperature for up to 31 days.

Humulin R U-500 vials can also be kept in the refrigerator or at room temperature after opening. But they must be used or discarded within 40 days of being opened.

Humulin R U-500 KwikPens can be used for up to 28 days after opening. But unlike vials of Humulin R, KwikPens should not be kept in the refrigerator once they’re opened. Instead, you should store Humulin R U-500 KwikPens at room temperature after opening.

How long can Humulin R be unrefrigerated?

Here’s a summary of how long each form of Humulin R can be kept unrefrigerated before it’s no longer safe for you to use.

  • Humulin R U-100 3-mL vial. Whether opened or unopened, if unrefrigerated, discard after 31 days.
  • Humulin R U-100 10-mL vial. Whether opened or unopened, if unrefrigerated, discard after 31 days.
  • Humulin R U-500 20-mL vial. Whether opened or unopened, if unrefrigerated, discard after 40 days.
  • Humulin R U-500 KwikPen. Whether opened or unopened, if unrefrigerated, discard after 28 days.

Disposal

Here, we describe how to properly dispose of both your needles and syringes and your leftover Humulin R.

Disposing of needles and syringes

After using a Humulin R U-500 KwikPen, discard the needle right away into a sharps container. (The pen can be used for additional doses.) And after using vials of Humulin R with needles and syringes, you’ll need to discard the needle and syringe right away into a sharps container. Don’t reuse needles or syringes when giving doses of Humulin R. (Doing so can cause infections.)

You can purchase sharps containers that are approved by the Food and Drug Administration (FDA). These containers can be found at online retailers, most pharmacies, and medical supply companies.

If you don’t have a sharps container, use a hard-sided, puncture-resistant container, such as an empty laundry detergent bottle. Be sure to label the bottle with a warning that shows it contains needles. And store the container out of reach from children and pets.

Disposing of Humulin R

If you no longer need to take Humulin R and have leftover medication, it’s important to dispose of it safely. This helps prevent others, including children and pets, from taking the drug by accident. It also helps keep the drug from harming the environment.

The FDA website provides several useful tips on medication disposal. You can also ask your pharmacist for information on how to dispose of your medication.

Here are answers to some frequently asked questions about Humulin R.

Is Humulin R a short-acting insulin?

Yes, Humulin R belongs to a class of medications called short-acting insulins. (A medication class is a group of medications that work in a similar way.) Short-acting insulins work to manage your blood sugar levels over a period of about 3 to 6 hours.

Humulin R takes about 30 minutes to start working after it’s taken. So, it needs to be taken about 30 minutes before meals. And it keeps working in your body for a total of about 8 hours after you inject your dose. But Humulin R works most effectively for about 3 to 6 hours after it’s taken.

Does Humulin R treat diabetic ketoacidosis?

The active drug in Humulin R, called insulin human, is sometimes used to treat diabetic ketoacidosis (DKA).

However, the drug is used a bit differently when treating this condition than it is when used routinely to treat diabetes. For example, instead of giving the drug as injection under your skin (called a subcutaneous injection), insulin human is given intravenously when treating DKA. (When given intravenously, the drug is injected into your vein over time. This is also called an IV infusion.)

DKA is a life threatening medical emergency. It happens in people with diabetes, when the cells in their body can’t take in enough glucose (sugar) to use for energy.

Symptoms of DKA can include:

  • breath that has a fruity odor
  • feeling thirsty or like your mouth is very dry
  • being tired
  • trouble breathing
  • urinating more often than usual
  • trouble concentrating or paying attention
  • high blood sugar level
  • nausea or vomiting

If you think you have DKA, call your doctor right away or go to the emergency room. If you feel you’re having a medical emergency, call 911. You should not attempt to treat DKA on your own using Humulin R.

Is Humulin R considered a mealtime insulin?

No, technically it’s not. Even though Humulin R must be given before a meal, it’s not a mealtime insulin.

The term “mealtime insulin” typically refers to rapid-acting insulins. These forms of insulin may also be called bolus insulin.

Rapid-acting insulins begin to work in as little as 5 minutes after they’re taken. And they reach their peak (highest) level about an hour after you inject them. Typically, rapid-acting insulins are given about 15 minutes before a meal. But some can be used immediately before you eat.

Humulin R is a “regular” or “short-acting” insulin. It takes about 30 minutes to start working after it’s taken. So it needs to be given about 30 minutes before your meals.

Can you mix Lantus and Humulin R?

No, you should not mix Lantus and Humulin R. The manufacturer of Lantus recommends that Lantus not be mixed with any other insulin product. And the manufacturer of Humulin R warns against mixing this drug with any other insulin.

Is it safe to use Humulin R for bodybuilding?

No, it’s not considered safe to use Humulin R for bodybuilding. In fact, Humulin R is not approved for increasing muscle size or improving athletic performance. Based on one study, over half of people using insulin for bodybuilding purposes experienced hypoglycemia (low blood sugar levels). And some people reported experiencing unconsciousness.

In our bodies, insulin tells our muscles to take in glucose (sugar). This action can help give your muscles energy during a workout. It also helps prevent muscle breakdown and can help build new muscle tissue.

However, insulin can also cause your blood sugar level to become low. This condition is called hypoglycemia. Severe hypoglycemia can lead to coma and even death.

The World Anti-Doping Agency and International Olympic Committee has banned the use of insulin as a performance enhancer. This means that athletes using insulin for this purpose risk being banned from competition. They also bear the health risks of misusing insulin.

The Food and Drug Administration (FDA) approves drugs such as Humulin R to treat certain conditions. Humulin R is FDA-approved to improve blood sugar levels in adults and children with either type 1 or type 2 diabetes.

Humulin R contains the active drug insulin human. It belongs to a class of medications called short-acting insulins. (A medication class is a group of medications that work in a similar way.) Short acting insulins work to manage your blood sugar level over about 3 to 6 hours.

Insulin human is a “recombinant” insulin. This means it’s made in a lab using special DNA technology that combines genetic material in order to make the insulin. This process allows the drug manufacturer to create an exact copy of the insulin that your body makes naturally.

Insulin is a hormone that helps move glucose out of your bloodstream and into your body’s cells. Once inside your cells, the glucose can be turned into energy.

With diabetes, your body is either not making insulin or not responding to insulin. This leads to increased blood sugar levels. (A high blood sugar level is called hyperglycemia.) Having high blood sugar levels can damage your organs. This includes organs such as your eyes, heart, kidneys, and nerves. And with high blood sugar levels, your cells might not be getting the glucose they need for energy.

Humulin R improves blood sugar levels by moving glucose out of your bloodstream and into your cells. This lowers your blood sugar level.

Effectiveness for diabetes

Humulin R has been effective in improving blood sugar levels in people with either type 1 or type 2 diabetes.

Before recombinant insulin was made, there weren’t any drugs available that were exact copies of the insulin naturally made by your body. At that time, drug manufacturers used insulin made by animals, including cows and pigs. The drug companies used this insulin to make insulin medications that could be given to people.

In clinical trials, insulin human (the active drug in Humulin R) was compared to animal insulin. The studies found that insulin human worked the same way in the human body as the animal-based insulins did.

Follow-up studies were done to compare the effects of the newly created insulin human drug with the effects of animal insulin. The studies found that insulin human worked as well as the older, animal-based insulins did in improving blood sugar levels in people with diabetes.

Humulin R and children

Humulin R is FDA-approved for use in children with either type 1 or type 2 diabetes. It’s used in children to manage blood sugar levels, just like it’s used in adults.

In people with diabetes, Humulin R may be used alone or in combination with other drugs to improve blood sugar levels.

Depending on both your condition and your blood sugar levels, you’ll likely take other diabetes drugs with Humulin R. It’s more common for people with type 2 diabetes to use more than one drug than it is for people with type 1 diabetes. But people with either condition may use more than one medication to help manage blood sugar levels.

If you have questions about using other diabetes drugs with Humulin R, talk with your doctor.

You should avoid drinking large amounts of alcohol while you’re taking Humulin R. Alcohol can affect your blood sugar levels and may increase your risk of either hypoglycemia (low blood sugar level) or hyperglycemia (high blood sugar level). In some cases, hypoglycemia can be dangerous or life threatening.

If you drink alcohol, talk with your doctor about how much is safe for you to drink while you’re using Humulin R.

Humulin R can interact with several other medications.

Different interactions can cause different effects. For instance, some interactions can interfere with how well a drug works. Other interactions can increase side effects or make them more severe.

Humulin R and other medications

Below are lists of medications that can interact with Humulin R. These lists do not contain all the drugs that may interact with Humulin R.

Before taking Humulin R, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Humulin R and other diabetes medications

Taking Humulin R with other drugs used to treat diabetes may increase your risk of hypoglycemia (low blood sugar level). In some cases, hypoglycemia can be severe.

If you’re taking other medications for diabetes, your doctor may need to change your Humulin R dose. They may also have you check your blood sugar level more often to monitor for hypoglycemia.

Examples of other diabetes medications include:

Humulin R and TZDs

In addition to the medications listed above, there’s a specific class of diabetes drugs called thiazolidinediones (TZDs) that also interact with Humulin R. (A class of drugs is a group of medications that work in a similar way.)

TZDs can cause fluid retention (swelling). They can also increase your risk of heart failure or make the condition worse if you already have heart failure. These risks of TZDs are increased when TZDs are used in combination with Humulin R.

Examples of TZDs include:

  • pioglitazone (Actos)
  • rosiglitazone (Avandia)

If you’re taking a TZD, talk with your doctor before starting Humulin R. They’ll discuss symptoms of new or worsening heart failure, which you should watch for if you’re taking Humulin R with a TZD. If you have new or worsened heart failure, your doctor may reduce your TZD dosage, or they may have you stop taking the TZD.

Humulin R and high blood pressure medications

Taking Humulin R with certain drugs used for high blood pressure may increase your risk of hypoglycemia (low blood sugar level). In some cases, hypoglycemia can be severe.

If you’re taking high blood pressure medications with Humulin R, your doctor may need to change your Humulin R dosage. They may also have you check your blood sugar level more often to monitor for hypoglycemia.

Examples of high blood pressure medications that may increase your risk of hypoglycemia when used with Humulin R include:

  • angiotensin converting enzyme (ACE) inhibitors, such as lisinopril (Zestril)
  • angiotensin II receptor blockers (ARBs), such as losartan (Cozaar)

In addition, other drugs used for high blood pressure may mask symptoms of hypoglycemia. This can make it hard for you to notice if your blood sugar level drops. These medications may also affect how well Humulin R works at lowering your blood sugar levels.

Examples of high blood pressure drugs that may mask symptoms of low blood sugar or affect how well Humulin R works include:

If you’re taking any of these medications, your doctor may need to change your Humulin R dosage. They may also have you check your blood sugar level more often to monitor for hypoglycemia.

Humulin R and other medications that affect your blood sugar level

If you take Humulin R with other medications that lower your blood sugar level, you may have an increased risk of severe hypoglycemia. (With severe hypoglycemia, you have a very low blood sugar level.)

Examples of medications that may lower your blood sugar level include:

If you’re taking any of these medications, your doctor may need to change your Humulin R dosage. They may also have you check your blood sugar level more often to monitor for hypoglycemia.

Humulin R and medications that can increase or decrease its effects

Some medications can affect how Humulin R works in your body. Some drugs may make Humulin R more effective at lowering blood sugar level, while other drugs may make it less effective.

Examples of medications that may affect Humulin R’s effectiveness include:

If you’re taking any of these medications, your doctor may need to change your Humulin R dosage. They may also have you check your blood sugar level more often to monitor for hypoglycemia.

Humulin R and herbs and supplements

There aren’t any herbs or supplements that have been specifically reported to interact with Humulin R. However, you should still check with your doctor or pharmacist before using any of these products while taking Humulin R.

Humulin R and foods

There aren’t any foods that have been specifically reported to interact with Humulin R. If you have any questions about eating certain foods with Humulin R, talk with your doctor.

As with all medications, the cost of Humulin R can vary. To find current prices for Humulin R in your area, check out GoodRx.com.


The cost you find on GoodRx.com is what you may pay without insurance. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Humulin R is available in an over-the-counter (OTC) form. The cost of the OTC form will be different from the cost of prescription Humulin R. However, it’s important to talk with your doctor before switching from prescription to OTC insulin. Your doctor will recommend the safest way for you to make this switch.

Your insurance plan may require you to get prior authorization before approving coverage for Humulin R. This means that your doctor and insurance company will need to communicate about your prescription before the insurance company will cover the drug. The insurance company will review the request and let you and your doctor know if your plan will cover Humulin R.

If you’re not sure if you’ll need to get prior authorization for Humulin R, contact your insurance company.

Financial and insurance assistance

If you need financial support to pay for Humulin R, or if you need help understanding your insurance coverage, help is available.

Eli Lilly and Company, the manufacturer of Humulin R, offers a savings card that may help lower the cost of your prescription. For more information and to find out if you’re eligible for support, call 866-923-1953 or visit the program website.

Humulin R is given by subcutaneous injection (an injection under your skin). When Humulin R is prescribed for you, your doctor or pharmacist will show you how to give yourself the drug injections. You should take Humulin R according to your doctor’s or healthcare provider’s instructions.

The manufacturer of Humulin R offers step-by-step instructions on how to give yourself an injection of Humulin R using a vial of the drug, insulin syringes, and needles. The instructions for Humulin R U-100 can be found on this web page. And instructions for Humulin R U-500 can be found on this web page. You can also watch a video that shows how to inject your dose of Humulin R U-500 using a needle and syringe on this website.

If you’re using the Humulin KwikPen, the drug manufacturer’s website offers specific instructions, including a video, on how to inject your dose. You can also view written directions on how to use the KwikPen on this web page.

It’s important to remember that you should never use syringes or needles more than once while taking Humulin R. (You’ll use both a needle and a syringe for your doses of Humulin R taken from a vial. And you’ll use just a needle with each dose taken from a KwikPen.)

After using these supplies for each dose, you should dispose of them right away into a sharps container. For more information about this, see the section “Humulin R expiration, storage, and disposal” above.

In addition, you should never share syringes or needles with other people or use these supplies more than once. Doing so can increase your risk of getting or spreading infection.

Note: Making changes to your insulin treatment plan without consulting your doctor could increase your risk for both hypoglycemia (low blood sugar levels) and hyperglycemia (high blood sugar levels). These changes may include administering your insulin differently than you usually do or injecting the drug into areas of skin that are thickened or pitted. They could also include taking a new dosage of insulin or using a new insulin product.

Injection sites

You’ll inject Humulin under the skin of your thighs, upper arms, belly, or buttocks. Make sure to rotate your injection sites with each dose to avoid certain side effects at the site of your injections. For more details on these side effects, see the “Humulin R side effects” section above.

When to take

Humulin R is typically taken two to three times daily, about 30 minutes before your meals. Your doctor will give you more information on the specific times that you should take your doses.

To help make sure that you don’t miss a dose, try setting a reminder on your phone. A medication timer may be useful, too.

Taking Humulin R with food

Humulin R needs to be taken with food. Specifically, you should take your dose of Humulin R about 30 minutes before a meal.

If you take Humulin R, but you don’t eat a meal shortly after getting your dose, you may have an increased risk of severe hypoglycemia (very low blood sugar level). In some cases, severe hypoglycemia can be fatal. It’s extremely important that you eat a meal within about 30 minutes after taking a dose of Humulin R.

If you have questions about taking Humulin R with food, talk with your doctor or pharmacist.

Humulin R is generally considered safe for use by people who are pregnant.

There’s a large amount of information that’s been collected over several decades on the use of insulin human during pregnancy. (Insulin human is the active drug in Humulin R.) This information hasn’t shown any association between insulin human use during pregnancy and an increased risk of birth defects or miscarriage. The information also hasn’t shown any relation to other bad outcomes for the mother or her fetus.

It’s important to note that uncontrolled diabetes during pregnancy can increase your risk of miscarriage, preterm birth, diabetic ketoacidosis (DKA),* and other serious complications. Because of this, it’s very important to manage your blood sugar levels if you have diabetes during pregnancy.

If you have concerns about using Humulin R during pregnancy, talk with your doctor.

* DKA is a life threatening medical emergency. It happens in people with diabetes when the cells in their body can’t take in enough glucose (sugar) to use for energy.

Humulin R is generally considered safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Humulin R.

In general, Humulin R is considered safe for use by people who are breastfeeding. Insulin human (the active drug in Humulin R) does pass into breast milk. But no side effects have been reported in infants who are breastfed by mothers taking insulin.

In fact, insulin is normally found in breastmilk. And it may decrease the risk of type 1 diabetes in a child who’s breastfed.

If you’re taking Humulin R and you have concerns about breastfeeding, talk with your doctor.

Before taking Humulin R, talk with your doctor about your health history. Humulin R may not be right for you if you have certain medical conditions or other factors affecting your health. These include:

  • Hypoglycemia. Using Humulin R with other diabetes medications may increase your risk of hypoglycemia (low blood sugar level). For more information, please see the “Humulin R interactions” and “Humulin R side effects” sections above. If you’re taking other medications for diabetes, talk with your doctor about your risk of hypoglycemia before you begin using Humulin R.
  • Risk of hypokalemia. All insulin products, including Humulin R, may cause hypokalemia (low potassium level). In some cases, this condition can be life threatening. People at high risk for hypokalemia must use insulin products with caution. This includes people who take either other medications that also lower potassium levels or medications that are affected by changes in blood potassium levels. Talk with your doctor before using Humulin R if you’ve been told that you have a risk for low potassium levels.
  • Risk of fluid retention and heart failure in people taking certain diabetes medications. When used with a class of diabetes medications known as thiazolidinediones (TZDs), Humulin R can increase your risk of fluid retention (swelling). Fluid retention may cause new or worsening heart failure. If you’re taking a TZD medication, such as Actos (pioglitazone) or Avandia (rosiglitazone), talk with your doctor before starting Humulin R.
  • Allergy to Humulin R. If you’re allergic to insulin human (the active drug in Humulin R) or to any other ingredients in Humulin R, you should not take this medication. If you aren’t sure about your medical allergies, talk with your doctor

Note: For more information about the potential negative effects of Humulin R, see the “Humulin R side effects” section above.

Using more than the recommended dosage of Humulin R can lead to serious side effects.

Overdose symptoms

Symptoms of an overdose can include:

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call the American Association of Poison Control Centers at 800-222-1222 or use their online tool. But if your symptoms are severe, call 911 or go to the nearest emergency room right away.

The following information is provided for clinicians and other healthcare professionals.

Indications

Humulin R is approved to improve glycemic control in both adults and children with diabetes mellitus. This drug can be used in people with either type 1 or type 2 diabetes.

Mechanism of action

Humulin R lowers blood glucose by increasing peripheral glucose uptake, especially by fat and skeletal muscle tissue. It also decreases blood glucose by inhibiting hepatic glucose production, lipolysis, and proteolysis.

Pharmacokinetics and metabolism

The pharmacokinetics and metabolism of Humulin R are both described below.

Humulin R duration

Humulin R U-100 has a duration of action of approximately 8 hours. The actual duration ranges from 3 hours to 14 hours.

The duration of action of Humulin R U-500 is approximately 21 hours. The actual duration ranges from 13 hours to 24 hours.

Humulin R insulin onset

Humulin R U-100 has an onset of action of approximately 30 minutes after administration. The actual range is 10 minutes to 75 minutes post dose.

Humulin R U-500 has an onset of action under 15 minutes.

Peak effect

The Humulin R U-100 peak effect occurs about 3 hours after dosing. The possible range for peak effect is anywhere from 20 minutes to 7 hours.

The peak effect of Humulin R U-500 occurs between 4 and 8 hours after dosing. The possible range for peak effect is anywhere from 0.5 hours to 8 hours.

Contraindications

Humulin R should not be used in people with hypersensitivity to Humulin R or any component of the drug product.

Humulin R should not be used during episodes of hypoglycemia.

Storage

Unopened Humulin R U-100 vials should be stored in a refrigerator, between 36oF and 46oF (2oC and 8oC). If unopened, Humulin R U-100 vials can be stored at room temperature for up to 31 days, as long as conditions remain below 86oF (30oC).

Unopened Humulin R U-500 KwikPens can be kept at room temperature for 28 days.

Unopened Humulin R U-500 vials can be kept at room temperature for up to 40 days.

Humulin R expiration after opening

After opening, Humulin R U-100 vials can be stored either refrigerated or at room temperature for up to 31 days.

Humulin R U-500 KwikPens can be used for up to 28 days after opening. Once opened, Humulin R U-500 KwikPens should be stored at room temperature. They should not be refrigerated.

Opened Humulin R U-500 vials can be kept in the refrigerator or at room temperature. Whether stored at room temperature or in the refrigerator, the vials must be used or discarded within 40 days.

Here’s a summary of long each form of Humulin R, whether opened or unopened, can be kept unrefrigerated before it is no longer safe for use:

  • Humulin R U-100 3-mL vial
    • discard after 31 days
  • Humulin R U-100 10-mL vial
    • discard after 31 days
  • Humulin R U-500 20-mL vial
    • discard after 40 days
  • Humulin R U-500 KwikPen
    • discard after 28 days

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.