8 EpiPen (Epinephrine) Side Effects and How to Manage Them
Key takeaways:
EpiPen (epinephrine) injections are a life-saving treatment for severe allergic reactions. But they may come with some side effects, such as anxiety, a fast heartbeat, and dizziness.
EpiPen side effects are usually temporary and resolve within a few hours. If your side effects won’t go away or worsen at any point, contact a healthcare professional.
You’re more likely to experience side effects if you have a health condition such as heart disease, high blood pressure, or diabetes. But if you’re experiencing a severe allergic reaction, the benefits of using an EpiPen outweigh the risks.
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Table of contents
EpiPen (epinephrine) is an auto-injector that’s FDA approved to treat anaphylaxis, a type of severe allergic reaction. This life-saving device comes prefilled with a single dose of epinephrine, so it’s quick and easy to use should you need it.
Epinephrine acts fast to reverse the effects of anaphylaxis. It does this by attaching to special proteins in your body called alpha- and beta-adrenergic receptors. This process effectively increases your blood pressure, heart rate, and opens up your airways. But you may experience some side effects at the same time.
EpiPen side effects at a glance
Relatively common and mild EpiPen side effects include:
Anxiety or nervousness
Shakiness
Restlessness
Dizziness
Weakness
Sweating
Headache
Fast heartbeat
Palpitations
Pale skin
Nausea
What does it feel like? Giving yourself an injection can seem scary. Three people share their stories on giving themselves injections and provide tips on how to make it easier.
Administration tips: Pharmacists provide essential instructions on how to use your EpiPen with confidence.
Disposal: Need to get rid of a used or expired EpiPen? Learn how to dispose of your auto-injector safely.
More serious EpiPen side effects may include injection reactions, high blood pressure, and heart problems.
Here, we’ll dive deeper into eight EpiPen side effects and how to manage them. And take note that these side effects can also occur with other injectable products that contain epinephrine, such as Auvi-Q and Adrenaclick.
1. Feeling anxious or nervous
When you’re having an allergic reaction, you’re already going to be anxious or nervous. An EpiPen could add to these feelings.
Epinephrine, or adrenaline, is a key player in your body’s fight-or-flight response. Think of a time you were in a stressful or scary situation. You might’ve noticed a racing heartbeat, sweaty palms, and you were probably nervous. These symptoms are a result of adrenaline.
When you use an EpiPen during an allergic reaction, epinephrine may cause you to feel the same way. This effect, though, is temporary and should gradually wear off.
2. Shakiness
After you inject an EpiPen, you may experience some shakiness or tremors. This can happen because epinephrine activates beta-2 receptors in the lungs and nerves. This is the same reason why other medications that affect beta-2 receptors, such as albuterol (Ventolin HFA), also cause shakiness. Thankfully, shakiness from an EpiPen shouldn’t last long. It should gradually wear off.
3. Dizziness
Your EpiPen may make you feel dizzy. There are a few reasons why this can happen. Epinephrine causes your blood vessels to constrict in order to direct blood flow to important organs; this movement of blood can cause you to feel faint. Anxiety, along with changes in heart rate and blood pressure, can add onto this and make dizziness worse.
If you’re feeling dizzy, it’s best to sit down to prevent falling down. This side effect should go away with time, especially after your allergic reaction is treated and under control.
4. Sweating
As mentioned earlier, epinephrine puts your body into fight-or-flight mode. Your heart will start to race, you’ll become more alert, and you may begin to sweat.
To alleviate this side effect, consider applying cold packs to your skin. You can also use a fan or turn on air conditioning while you’re waiting for emergency services to arrive. (You should always call 911 or seek emergency medical help after administering a dose of epinephrine.)
5. Headache
Headaches are a common side effect of epinephrine. They’re generally caused by blood vessel constriction and blood pressure changes. If you have a headache after using an EpiPen, know that it should be temporary and subside with rest.
You can manage your headache, if needed, with over-the-counter medications such as ibuprofen (Advil, Motrin) and acetaminophen (Tylenol). But if your headache persists or gets worse — especially after your allergic reaction has resolved — get help from a healthcare professional right away. This may be a sign of something more serious, like a cerebral hemorrhage. This occurs when your blood pressure rises quickly, causing a blood vessel in the brain to burst.
6. Injection reactions
Injection site reactions, such as redness and swelling, can develop after using an EpiPen. This is especially true if you inject it by accident or into a non-recommended area of your body.
You should only inject an EpiPen into the outer thigh. If you accidentally inject your EpiPen into another part of the body — like your hands or feet — you should seek medical help right away. This is because the medication can restrict blood flow to these smaller areas.
You should also avoid injecting an EpiPen into the buttocks. By doing so, your EpiPen may not be effective. It can also increase the risk of a serious skin infection called gas gangrene. If you inject an EpiPen into the buttocks, seek medical attention right away.
7. High blood pressure
During an episode of anaphylaxis, you may experience a rapid drop in blood pressure. This can lead to shock, which happens when organs don’t receive enough blood flow and oxygen as a result of low blood pressure. This can lead to organ damage or failure.
An EpiPen is designed to reverse this process. After administering a dose, the medicine begins to raise your blood pressure to improve blood flow throughout the body. An EpiPen can cause high blood pressure for this reason.
This side effect is temporary and shouldn’t last long. But it can be dangerous in people who have a pre-existing heart condition or high blood pressure. This is because people who have these conditions are more likely to develop chest pain or a cerebral hemorrhage from this spike in blood pressure.
Keep in mind: EpiPen doesn’t have any restrictions for use. It should always be used in the event of anaphylaxis, even in those with a pre-existing heart condition.
8. Heart palpitations and other heart problems
Epinephrine causes your heart to beat faster and stronger to fight the effects of anaphylaxis. This may lead to temporary heart palpitations, which is a normal and expected side effect.
However, this can be dangerous for those who have a pre-existing heart condition. Some people have reported irregular heart rhythms after using an EpiPen.
Again, it’s recommended to use an EpiPen in the event of anaphylaxis — even if you have a heart condition. The benefits of treating anaphylaxis far outweigh the risks. To stay prepared, though, make sure to discuss any health conditions with your healthcare professional so they can guide you on safe use and what to expect.
Frequently asked questions
Side effects from your EpiPen should only be temporary and get better with rest. They will typically start to subside in about 30 minutes and resolve in a couple of hours.
Yes, epinephrine can increase blood glucose (sugar). It does this by telling your liver to increase glucose production. Epinephrine can raise blood sugar by about 30 mg/dL in people without diabetes. This number is typically higher in people who have diabetes, and stays higher for a longer period of time.
If you inject an EpiPen without needing it, you may experience side effects such as high blood pressure, a fast or pounding heart beat, or anxiety. But if you’re having an allergic reaction and are unsure if you need an EpiPen, it’s better to use it to be safe. The benefits of the medication outweigh the risks of an unnecessary dose.
The bottom line
You should use an EpiPen (epinephrine) in the event of anaphylaxis, a type of severe allergic reaction. Any side effects from the medication should resolve fairly quickly with rest — typically within a few hours. You may be at a higher risk of side effects if you have a pre-existing condition, such as heart problems, high blood pressure, or diabetes.
Regardless if you experience EpiPen side effects or not, it’s important to seek medical attention after administering it. Using an EpiPen for a severe allergic reaction doesn’t replace the need for follow-up medical care in a hospital.
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References
Alshak, M. N., et al. (2023). Neuroanatomy, sympathetic nervous system. StatPearls.
Allergy and Asthma Network. (n.d.). What is epinephrine?
American College of Allergy, Asthma & Immunology. (2018). Epinephrine auto-injector.
Amneal Pharmaceuticals of New York. (2021). Epinephrine injection [package insert].
Buboltz, J. B., et al. (2023). Gas gangrene. StatPearls.
Cazzola, M., et al. (2012). Tremor and β2-adrenergic agents: Is it a real clinical problem? Pulmonary Pharmacology & Therapeutics.
Dalal, R. (2024). Epinephrine. StatPearls.
Sherwin, R. S., et al. (1980). Epinephrine and the regulation of glucose metabolism: Effect of diabetes and hormonal interactions. Metabolism: Clinical and Experimental.
Sherwin, R. S., et al. (1984). Effect of epinephrine on glucose metabolism in humans: contribution of the liver. American Journal of Physiology: Endocrinology and Metabolism.
Viatris Specialty. (2023). Epipen [package insert].
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