Basaglar (insulin glargine) is a brand-name prescription medication. It’s approved by the Food and Drug Administration (FDA) to improve blood sugar levels in:

The drug is typically used long term.

Here are some fast facts about Basaglar:

Like other drugs, Basaglar can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Basaglar, including details about its uses, read this article.

Basaglar can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects* reported by people who took Basaglar in clinical trials:

  • injection site reactions, such as pain, itching, swelling, or irritation where you inject the drug
  • swelling in the feet or lower legs due to fluid buildup
  • low blood sugar
  • skin rash
  • weight gain†
  • skin changes at injection sites†

* Basaglar contains the active ingredient insulin glargine. These side effects were also reported by people who took similar drugs that contain insulin glargine, such as Lantus.
† For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Basaglar. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Basaglar’s prescribing information.

Mild side effects* that have been reported with Basaglar include:

  • injection site reactions, such as pain, itching, swelling, or irritation where you inject the drug
  • swelling in the feet or lower legs due to fluid buildup
  • itchy skin
  • common cold symptoms, such as a runny nose
  • skin rash
  • weight gain†
  • skin changes at injection sites†

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Basaglar and want to tell the FDA about it, visit MedWatch.

* Basaglar contains the active ingredient insulin glargine. These side effects were also reported by people who took similar drugs that contain insulin glargine, such as Lantus.
† For more information about this side effect, see “Side effect specifics” below.

Basaglar may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Basaglar’s prescribing information.

If you develop serious side effects while taking Basaglar, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects* that have been reported with Basaglar and their symptoms include:

* Basaglar contains the active ingredient insulin glargine. These side effects were also reported by people who took similar drugs that contain insulin glargine, such as Lantus.
† For more information about this side effect, see “Side effect specifics” below.

Basaglar is approved for use in children ages 6 years and older with type 1 diabetes. The side effects of the drug in children are similar to those in adults. However, children are more likely to have hypoglycemia (low blood sugar) with Basaglar. And this side effect is more likely to be severe in children.

If your child is prescribed Basaglar, their doctor will advise you and your child on how often to monitor blood sugar. It’s important that you and your child recognize the symptoms of hypoglycemia and know what to do if they occur.

For more information about low blood sugar, see “Side effect specifics” below.

Basaglar may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

I’m using the Basaglar KwikPen. Are any side effects specific to this form of the drug?

No, Basaglar’s possible side effects are the same with whichever form of the drug you take.

However, keep in mind that Basaglar KwikPens deliver a maximum of 80 units per injection. If your dose is higher than 80 units, you’ll need to give yourself more than one injection to complete each dose. Multiple injections may increase the risk of certain side effects. These include injection site reactions and lipodystrophy (thickening, pitting, or other changes in your skin at injection sites).

For more information about these side effects, see “Side effect specifics” below. You can also talk with your doctor or pharmacist.

Can taking Basaglar with other insulins and diabetes medications cause side effects?

It’s possible. Taking Basaglar in combination with other insulins and diabetes medications can increase your risk of side effects. This includes low blood sugar. For this reason, it’s very important to monitor your blood sugar levels. Your doctor can show you how to check your blood sugar at home and advise you on how often to do it.

It’s common for doctors to prescribe Basaglar with other insulins and diabetes medications. For example, people with type 1 diabetes typically take short- or rapid-acting insulin at mealtimes during Basaglar treatment. (Basaglar is a long-acting insulin.)

Your doctor will monitor you for side effects of your diabetes medications. When adding or changing them, your doctor may adjust your dosages. They’ll also likely have you monitor your blood sugar level more often than usual.

If you have any questions about possible side effects of Basaglar or other diabetes medications, talk with your doctor or pharmacist.

Are the side effects of Basaglar the same as the side effects of Lantus, Semglee, or Toujeo?

The side effects of Basaglar, Lantus, Semglee, and Toujeo are expected to be the same. This is because all four medications contain the same active ingredient: insulin glargine.

Your doctor will prescribe the best insulin for you based on several factors. These may include your overall health, how active you are, and how well managed your blood sugar levels are. Also, certain brands of insulin glargine may cost less than others, and your doctor can consider this as well.

If you’d like to learn more about the side effects of Basaglar and other diabetes treatments, ask your doctor or pharmacist.

This section covers more details about some of the side effects that Basaglar may cause.

Skin rash

Basaglar may cause a skin rash in some people. Symptoms may include skin discoloration or redness, swelling, and itching.

It isn’t clear how often a skin rash occurred in clinical trials of Basaglar. The drug’s manufacturer reported that this side effect was common.

What you can do

If you have a mild skin rash while taking Basaglar, it will usually go away without treatment. Until then, try to avoid injecting Basaglar into areas affected by the rash. Be sure to rotate your injection site so that you don’t use the same spot for each dose. And you should use a new needle with every injection. These tips may also help prevent a rash.

Keep in mind that a skin rash may also be a symptom of an allergic reaction. So it’s important to tell your doctor if you develop a rash while taking Basaglar, especially if it’s severe or doesn’t go away. They can help determine if you’re having an allergic reaction and what the next steps should be. For more information about allergic reactions with Basaglar, see “Allergic reaction” below.

Weight gain

Weight gain is a common side effect of insulins, including Basaglar. It isn’t clear how often weight gain occurred in clinical trials of the drug. However, the manufacturer of Basaglar reported that this side effect was common.

As a type of insulin, Basaglar helps lower high blood sugar levels that can occur in people with diabetes. Insulin works by helping cells absorb sugar from food so your body can use it as a source of energy. However, if you consume more food than you need, the extra sugar is stored as fat. This can lead to weight gain.

What you can do

It may be possible to reach and maintain a moderate weight during Basaglar treatment. These tips can help:

If you’re concerned about weight gain with Basaglar, talk with your doctor about a diet and exercise plan that’s right for you. They may also refer you to a dietitian or diabetes specialist.

Skin changes at injection sites

Basaglar injections may cause a condition called lipodystrophy (changes in the fatty tissue layer under your skin). Lipodystrophy can alter your skin texture or appearance where you inject the drug. These changes include skin thickening, pitting, and indentations.

Basaglar injections may also cause a condition called localized cutaneous amyloidosis. This condition causes clumps of proteins to build up in the skin, forming lumps.

It isn’t known how often skin changes occurred in clinical trials of Basaglar. However, skin thickening, pitting, dents, and lumps are common side effects of insulin. (Basaglar is a type of insulin.)

Your body may not absorb Basaglar correctly if you inject it into areas of skin affected by these conditions. For example, if you repeatedly inject the drug into areas of thickened skin, your blood sugar level may become too high. Suddenly switching your injection site to an unaffected area may cause your blood sugar level to drop too low.

What you can do

You’ll inject Basaglar under the skin of your abdominal area, thighs, or upper arms. To help prevent or minimize skin changes, avoid using the same spot repeatedly for injections. Instead, rotate your injection site for each dose. You should also use a new needle with every injection.

You should avoid injecting Basaglar into areas that are tender, bruised, or hard. In addition, try not to inject into skin that’s scaly, scarred, or damaged. If you already have areas of thickened, pitted, or lumpy skin due to injecting insulin, do not choose these areas as injection sites.

If you have concerns about skin changes during your Basaglar treatment, talk with your doctor or pharmacist.

Low blood sugar

Low blood sugar (also called hypoglycemia) is a common side effect of insulins, including Basaglar. Low blood sugar was commonly seen in clinical trials of the drug.

Low blood sugar usually causes mild symptoms at first. However, symptoms may become serious and life threatening if not treated right away.

Symptoms of mild hypoglycemia can include:

  • shakiness
  • hunger or crankiness
  • dizziness
  • sweating
  • headache
  • nausea
  • fast heartbeat

Symptoms of severe hypoglycemia can include:

Certain factors, such as injecting too much Basaglar, can increase the risk of low blood sugar during treatment. Other factors may include eating less than usual, exercising more than usual, and using other insulins or certain medications.

What you can do

To help prevent low blood sugar, follow your doctor’s instructions for monitoring your blood sugar level at home. They’ll likely have you check it more often in certain situations, such as when your dosage of Basaglar or other medications is adjusted. Other situations can include when you start a new diet or exercise program or when you’re ill.

If you have symptoms of low blood sugar, you should try to raise your level as soon as possible. You can do this by consuming a sugary food or beverage right away. In some cases, you may need another person to help you. Keep in mind that a diet soda or a diet or sugar-free candy won’t treat low blood sugar.

Before you start Basaglar treatment, your doctor will go over what to do if you have low blood sugar. They may prescribe a medication called glucagon (Gvoke, Baqsimi, others), which is used to treat severe episodes of low blood sugar.

Allergic reaction

As with most drugs, Basaglar can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Basaglar. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Basaglar. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Liver or kidney problems. If you have liver or kidney problems, you may have an increased risk of hypoglycemia with Basaglar. Talk with your doctor about whether the drug is right for you.

Low level of potassium. Basaglar can cause a low level of potassium in your blood, which is also known as hypokalemia. If you already have a low level of potassium, Basaglar could worsen this condition. If your potassium level is low or you take other medications that can lower potassium levels, talk with your doctor. They may monitor your potassium levels during your Basaglar treatment.

Heart problems. If you have heart failure or another heart problem and take a thiazolidinedione, such as pioglitazone (Actos), Basaglar may not be safe for you. Taking a thiazolidinedione in combination with Basaglar can cause edema. This may worsen heart problems, including heart failure. Your doctor may recommend a different treatment for your diabetes.

Low blood sugar episode. Taking Basaglar during an episode of low blood sugar can increase the risk of severe side effects. Due to this risk, doctors typically won’t prescribe Basaglar for that purpose. Your doctor can suggest other medications.

You can take Basaglar once your blood sugar level has returned to normal. However, if you have repeated episodes of low blood sugar, your doctor may adjust your dose of Basaglar or have you stop taking the medication. They may recommend other treatments.

Diabetic ketoacidosis. If you develop a serious complication of diabetes called diabetic ketoacidosis, your doctor will usually not manage your blood sugar with Basaglar during this time. They can suggest other treatments.

Allergic reaction. If you’ve had an allergic reaction to Basaglar or any of its ingredients, your doctor will likely not prescribe Basaglar. Ask them what other medications may be better options for you.

Alcohol use with Basaglar

It may not be safe to drink alcohol during Basaglar treatment. Alcohol isn’t known to interact with the drug, but alcohol can make your blood sugar levels more difficult to manage.

Consuming alcohol may cause your blood sugar levels to fluctuate. This can increase the risk of hypoglycemia. Basaglar can also cause hypoglycemia. So drinking alcohol and taking Basaglar may increase your risk further. For more details about hypoglycemia, see the “Side effect specifics” section above.

If you drink alcohol, talk with your doctor about how much, if any, is safe for you to consume during Basaglar treatment.

Pregnancy and breastfeeding while taking Basaglar

It isn’t known for sure if Basaglar is safe to take while pregnant or breastfeeding because research is limited. However, the drug isn’t known to cause harmful effects in a developing fetus or child who is breastfed.

Tell your doctor if you’re pregnant, planning to become pregnant, or breastfeeding. They can recommend a treatment plan that’s best for managing your diabetes during this time.

Basaglar may cause side effects, but most are mild or easily managed. Serious side effects are also possible, especially in certain people or situations.

Before starting Basaglar treatment, talk with your doctor about your risk of side effects such as hypoglycemia (low blood sugar). For details about hypoglycemia, see “Side effect specifics” above.

If you’d like to learn more about Basaglar, talk with your doctor or pharmacist. They can help answer any questions you have about side effects of taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Basaglar. For details about other aspects of Basaglar, refer to this article.
  • Drug comparison. To learn how Basaglar compares with similar drugs, see this article.
  • A look at diabetes. For details about your condition, see our diabetes hub as well as this list of diabetes articles.

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 another 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.