EpiPen (epinephrine) is a brand-name injection prescribed for the emergency treatment of a severe allergic reaction in adults and children. As with other drugs, EpiPen can cause side effects, such as anxiety, shaking, and restlessness.

EpiPen can cause certain side effects, some of which are more common than others. People who have high blood pressure, heart disease, or overactive thyroid may have an increased risk of such side effects.

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

Below are just a few of the more common side effects reported in clinical trials, certain case reports, and other studies:

Mild side effects can occur with EpiPen use. People with high blood pressure, heart disease, or overactive thyroid may have an increased risk of side effects.

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

Mild side effects that have been reported with EpiPen include:

These side effects may be temporary, lasting a few hours or days. However, if they 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 and reviews side effects of the medication. If you develop a side effect while taking EpiPen and want to tell the FDA about it, visit MedWatch.

Serious side effects from EpiPen use are rare but some groups have an increased risk. This includes older adults (those aged 65 years and older) and people with diabetes, overactive thyroid, or existing heart disease.

This increased risk should not be a reason to avoid using an EpiPen if it’s needed in an emergency situation. For more information about this, talk with your doctor.

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

If you develop serious side effects while taking EpiPen, 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 and their symptoms include:

ALLERGIC REACTION

EpiPen is prescribed to treat severe allergic reactions, including anaphylaxis. In some people, EpiPen injection can cause an allergic reaction if those people have an allergy to sulfites. It’s not clear whether this side effect occurred in the drug’s studies. Note that EpiPen is still the preferred drug treatment option for anaphylaxis, even in people with sulfite allergies.

In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to EpiPen injection, your doctor may recommend taking a different medication instead.

Note: After using EpiPen, you should always seek immediate medical care. You may need further treatment for the allergic reaction you’re using EpiPen to treat.

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

Does EpiPen cause side effects the next day?

It’s not likely. EpiPen’s active ingredient (epinephrine) begins working right away and wears off quickly, usually after about 120 minutes. In most cases, this means its side effects will resolve within a few hours. Rest may also help your side effects go away.

If you experience side effects that bother you or persist after using an EpiPen, talk with your doctor right away.

Note: You should always seek immediate medical care after using EpiPen. You may need further treatment for the allergic reaction you’re using EpiPen to treat.

What does an EpiPen do to a “normal” person?

In someone who isn’t experiencing an allergic reaction, EpiPen can cause an increase in blood pressure and heart rate. Also, if an unnecessary dose is given in the finger or hand, you may experience a reduction in blood flow to the area.

EpiPen contains the active ingredient epinephrine (also known as adrenaline). It’s a hormone that causes several effects in your body. These include narrowing your blood vessels, relaxing and opening your airways, and increasing the strength and speed of your heartbeat. These effects are essential for treating anaphylaxis (a severe allergic reaction).

If you accidentally receive a dose of EpiPen when it wasn’t needed, get medical help right away.

How long do side effects of epinephrine last?

Most side effects of EpiPen are temporary and will go away within about 120 minutes. The side effects may also go away with rest.

If you’re experiencing side effects that don’t go away, talk with your doctor.

Learn more about some of the side effects that EpiPen may cause.

Arrhythmia

Rare instances of arrhythmia (irregular heart rhythm) have been reported with EpiPen use.

Not all arrhythmias cause symptoms, but if they do, symptoms may include:

The risk of arrhythmia with EpiPen use is higher in certain people, including those who:

What you can do

If you experience any signs or symptoms of an irregular heart rhythm, get medical help right away. Your doctor can run tests to see if you need treatment. They can also help determine if EpiPen is safe for you to use in the future.

Note: After using EpiPen, you should always seek immediate medical care. You may need further treatment for the allergic reaction.

Serious skin and soft tissue infections

Serious skin and soft tissue infections were rare in people using EpiPen.

Examples of these infections include gangrene and necrotizing fasciitis (flesh-eating disease). These infections occurred in the area where EpiPen was injected and can appear within a few days of injecting the drug.

Symptoms of skin or soft tissue infections include:

  • skin discoloration such as redness that doesn’t go away
  • swelling
  • tenderness
  • skin warmth that doesn’t go away

What you can do

To lower the risk of infections, avoid injecting EpiPen into your buttock. If you develop any symptoms of infection, talk with your doctor right away. They can evaluate the area and determine if you have an infection. If so, they can recommend treatment.

For more information about how to use EpiPen, see this article.

Below is important information you should consider before using EpiPen.

Discuss with your doctor whether EpiPen is right for you. People with certain medical conditions or other factors affecting their health may need to use EpiPen with caution. Be sure to talk with your doctor if any of the following apply to you:

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.