What is Epinephrine?


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Epinephrine, also known as adrenaline, is both a hormone and a medication. A person’s adrenal glands produce epinephrine, which helps to regulate organ functions. It is typically released when the body is under stress. It is part of the fight or flight response. Let’s say something startles you and you feel your pulse racing and the color drains from your skin. That’s all from the release of epinephrine.

But, like many things in medicine, epinephrine has other purposes. Epinephrine medication is a helpful tool in treating medical emergencies. It is the first line treatment for life-threatening allergic reactions known as anaphylaxis.

Woman pulling cap off auto-injector

What is epinephrine used for?

When most people think of epinephrine, they think of its use in treating a serious allergic reaction, or an anaphylactic episode.

Epinephrine has other uses, primarily to treat heart-related conditions, but these are only used in emergency situations in a hospital. Epinephrine inhalers are sometimes used to treat an asthma attack but not for symptoms of anaphylaxis.

Let’s explore the use of epinephrine for treating anaphylaxis.

What does epinephrine do?

Epinephrine has different effects on different parts of the body including:

  • Heart — it causes the heart to pump faster and harder. This raises your blood pressure and circulates blood more quickly throughout the body.
  • Lungs and airways — your breathing becomes deeper and faster. It dilates the airways and may reduce swelling.
  • Eyes — it causes the pupils in your eyes to dilate.
  • Skin — it becomes pale, as blood is diverted to your major organs and muscles.
  • Muscles — they have increased blood flow.

When an epinephrine injection is given, it does all of this simultaneously. It also gives some people the feeling of being hyper or anxious.

All of the above are all normal and expected effects of epinephrine.

Two EpiPens side by side

Epinephrine for anaphylaxis

Epinephrine is the first line treatment for severe anaphylaxis. Anaphylaxis is a severe allergic reaction that can occur due to:

  • food allergy

  • medication allergy

  • insect stings or insect venom allergy

  • latex allergy

  • vaccine allergy (in rare cases)

Food-induced anaphylaxis is the most common type of anaphylaxis.

In rare cases, people can experience exercise-induced anaphylaxis. This can be a serious allergic reaction. It may occur after eating food and then exercising vigorously.

People with any of these allergies and their caregivers may need anaphylaxis education on:

  • how to prevent allergic reactions;

  • how to recognize signs of anaphylaxis;

  • how to treat anaphylaxis.

Epinephrine is the first line treatment for an anaphylactic episode. It provides immediate symptom relief. Do not substitute antihistamines for epinephrine. Antihistamines only treat a few symptoms such as hives and they take about 30 minutes to have an effect. Epinephrine will treat a life-threatening allergic reaction immediately – antihistamines will not.

What are the effects of epinephrine when given for anaphylaxis?

You may be asking why it’s so important to use epinephrine for a serious allergic reaction.

Well, let’s think about what happens in an anaphylactic reaction. People may experience throat swelling and difficulty breathing. The blood pressure may drop. They may develop hives or other allergic reaction symptoms.

Epinephrine use in anaphylaxis reduces or reverses these severe symptoms very quickly. It works by reducing throat swelling. It opens the airways. It helps maintain heart function and blood pressure. Also, as epinephrine causes the blood to be diverted away from the skin, it can help reduce hives and itching. Epinephrine will also prevent a further release of histamine, the chemical that responds to allergens and ushers in symptoms.

Remember that an anaphylactic reaction causes life-threatening symptoms. If not quickly treated, these symptoms can lead to anaphylactic shock and death. Epinephrine works by immediately reversing these severe allergic reactions. So, remember, epinephrine first and epinephrine fast. Don’t delay.

Note: always call 911 when epinephrine is administered. Sometimes a second dose of epinephrine is needed to treat a second anaphylactic reaction, called biphasic anaphylaxis. Further monitoring from healthcare professionals is necessary.

When do you need an epinephrine injection?

Epinephrine should be given immediately at the first sign of a serious allergic reaction, or anaphylaxis. Anaphylaxis is diagnosed when symptoms involve two or more body organ systems: skin, mouth and/or throat, stomach, lungs and airways, and heart.

It is crucial to recognize anaphylaxis and treat it immediately. When you see signs of an anaphylactic reaction, epinephrine is the first line treatment. Death due to anaphylaxis is often due to a delay in administering epinephrine.

What are the symptoms of anaphylaxis?

Anaphylaxis is diagnosed when symptoms appear on two or more body organ systems. Anaphylaxis symptoms involve:

  • Skin: itching, redness, swelling, hives that are widespread across the body
  • Mouth and/or throat: itching, swelling of lips, tongue
  • Stomach: vomiting, diarrhea, cramps
  • Respiratory: trouble breathing, shortness of breath, wheezing, coughing, chest pain and/or tightness
  • Heart: weak pulse, dizziness, faintness
  • Headache, nasal congestion, watery eyes, sweating
  • Confusion, feeling of impending doom
  • Loss of consciousness

How fast does epinephrine work?

Epinephrine begins to work immediately after it is injected. However, its full effect may take 5-10 minutes. It begins wearing off within 20-30 minutes. Therefore, people must seek emergency care after administering epinephrine.

Sometimes the epinephrine wears off before the allergic reaction has subsided. Biphasic reactions also may occur where symptoms return again. A second dose of epinephrine and other medical support may be needed.

Person's hand holding an EpiPen so the label shows

What is the epinephrine mechanism of action in severe allergic reactions?

When epinephrine is injected, it triggers a sudden burst of adrenaline to multiple areas of the body simultaneously. Your heart begins to beat faster and stronger. Your airways open. The blood goes to your vital organs and away from your skin.

All of a sudden, you breathe easier. You stop itching and feel less lightheaded, and your pulse stops racing. Epinephrine is so effective, it reverses the life-threatening allergic reaction.

Two EpiPens and an inhaler in the back of a backpack

What are the side effects of epinephrine?

Like any medication, side effects from epinephrine may occur. These may include:

  • Trouble breathing
  • Fast, irregular, or pounding heartbeat
  • Pale skin
  • Sweating
  • Nausea and/or vomiting
  • Dizziness
  • Weakness or tremors
  • Headache
  • Anxiety or restlessness

How long do side effects of epinephrine last?

Epinephrine is a relatively quick-acting medication. It begins to work immediately and wears off quickly. The side effects don’t last very long. Most of the side effects should start to resolve within about 30 minutes and fully disappear within a few hours.

Is epinephrine dangerous?

Epinephrine is very safe. As a first line treatment, epinephrine is the only medication that can reverse the life-threatening allergic reaction symptoms. When given the correct way and at the correct dose, it is a very safe medication.

You may think that since people are advised to call 911 after epinephrine, the medication may not be fully safe. That is not the reason. You should call 911 because epinephrine wears off within about 30 minutes. You may need another injection or additional treatment and monitoring.

Once at the hospital, you may need another dose of epinephrine. Epinephrine may be given intravenously (IV) for patients in cardiac arrest or as an IV drip for low blood pressure.

The concern for the safety of epinephrine is normally due to it being given incorrectly — either a dose too high or by the wrong route of administration.

Can you be allergic to epinephrine?

A true allergy to epinephrine is extremely rare. After all, epinephrine is naturally occurring within the human body. A dose of epinephrine is not going to cause an allergic reaction.

In rare cases, people with an allergy to sulfite preservatives in epinephrine have experienced allergic reactions. Sodium bisulfites are commonly added to epinephrine-containing solutions to serve as an antioxidant and increase the shelf-life for these agents. These cases are nearly always mild. The benefits of taking the medication far outweigh the risks from an allergic reaction to sulfite. Preservative-free epinephrine is available as well.

Epinephrine is the only medication that can reverse the life-threatening symptoms of an anaphylaxis.

Does epinephrine increase blood pressure?

Epinephrine does raise blood pressure, but only temporarily. The effects normally wear off after about 30 minutes.

People diagnosed with heart disease should talk with their doctor about the potential impact epinephrine may have on their condition. If a person with heart disease experiences life-threatening anaphylaxis, epinephrine should still be given.

The benefits of epinephrine in treating life-threatening symptoms far outweigh the risks, even concerning other medical conditions.

Does epinephrine increase heart rate?

Epinephrine raises the heart rate temporarily. The effects will only last until the medication wears off.

Again, people diagnosed with heart disease should talk with their doctor about the potential impact epinephrine may have on their condition. Epinephrine should still be given to treat life-threatening allergic reactions — the benefits far outweigh the risks.

Is epinephrine a steroid?

Epinephrine is not a steroid. It is a naturally occurring hormone produced by the adrenal glands.

Woman's hands opening epinephrine autoinjector case

How is epinephrine given for anaphylaxis?

Epinephrine is most often administered via an auto-injector. It can also be delivered manually through a syringe and needle. Both the auto-injector and manual injection deliver epinephrine into the muscle of the outer thigh. This is referred to as an intramuscular epinephrine injection.

Using an auto-injector is preferable for most people. The reason is that the medication comes pre-filled with epinephrine solution and the needle attached. All it requires is the user to follow the auto-injector instructions to release the epinephrine into the muscle of the outer thigh.Epinephrine auto-injectors are considered more user friendly and leave less room for error.

Using the manual method, the epinephrine would first need to be drawn up in a syringe. Then you would attach a needle to the syringe. This creates room for error and takes longer, thus delaying emergency treatment. (Some syringe kits do come pre-filled with the epinephrine solution and needle attached. Ask your doctor if these kits are available.)

Some people may choose to use the manual method because it’s a much cheaper alternative than epinephrine auto-injectors. Epinephrine auto-injectors may cost anywhere from $100 to several hundred dollars, depending on insurance. Meantime, ampules of epinephrine and syringes/needles can be purchased for around $20.

Clinical trials are underway for new routes of epinephrine administration to treat severe reactions. Sublingual epinephrine (under the tongue) shows promising results for treating anaphylaxis. An epinephrine nasal spray may also be another option for anaphylaxis treatment in the future.

Is there a general epinephrine dose for anaphylaxis?

For adults experiencing severe symptoms of an anaphylactic reaction, the standard dose for treatment is 0.3-0.5 mg via intramuscular injection. This may be repeated every 5-10 minutes as needed.

For children experiencing severe symptoms of an anaphylactic reaction, the standard dose is 0.15 mg (under 66 pounds) to 0.3 mg (over 66 pounds) via intramuscular injection. This may be repeated every 5-10 minutes as needed.

For very young children, the epinephrine brand AUVI-Q® has a dosage of 0.10 mg (16.5 t0 33 pounds). Talk with your child’s doctor about this option.

Hospitals and emergency departments use vials and syringes to administer epinephrine. When prescribing epinephrine, hospital and emergency room staff will provide a specific dosage based on the patient’s body weight.

How is epinephrine administered in an emergency?

Epinephrine is given via intramuscular injection into the middle outer thigh muscle. If you’re using an epinephrine auto-injector, follow the instructions for your specific brand.

There is no need to remove clothing to do this — give the injection right through the clothes if needed.

How do you inject epinephrine?

Different epinephrine auto-injectors may function differently. Familiarize yourself with your specific type of auto-injector. Ask your doctor for anaphylaxis education resources. Generally, the process for administering an epinephrine auto-injector is as follows:


  • Take off the cap.

  • Press the tip firmly on the thigh at a perpendicular (right) angle.

  • Swing and push the auto-injector firmly until you hear a click.

  • Hold firmly for 10 seconds.

  • Remove the auto-injector.

  • Massage area for 10 seconds.

  • Call 911 for continued monitoring and in case you need a second injection to treat biphasic anaphylaxis.

  • Discard auto-injector (preferably in a sharps container, which you can get at any pharmacy) or bring it with you when going to the hospital or emergency room.

Woman's hands holding two epinephrine autoinjectors

Are epinephrine auto-injectors the same dosage?

Epinephrine auto-injectors typically come in 2 doses:

  • 0.10 mg (for children 16.5 to 33 pounds) — AUVI-Q brand only
  • 0.15 mg (for children under 66 pounds)
  • 0.3 mg (for children and adults over 66 pounds)

How to use a generic epinephrine auto-injector?

Generic epinephrine auto-injectors are available. They may have slightly different instructions, so it is important to review the instructions on your auto-injector. In general, the process is very similar to most brand auto-injectors:

  • Take off the cap.
  • Press the tip firmly on the thigh at a perpendicular angle.
  • Swing and push the auto-injector firmly until you hear a click.
  • Hold firmly for 10 seconds.
  • Remove the auto-injector.
  • Massage area for 10 seconds.
  • Call 911 for continued monitoring and in case you need a second injection to treat biphasic anaphylaxis.
  • Discard auto-injector or bring it with you when going to the hospital or emergency room.

Where should auto-injectors be injected?

Epinephrine auto-injectors should be injected directly into the muscle of the middle outer thigh. Injections may sometimes be given under the skin, but the muscular injection is more effective.

Is an auto-injector an EpiPen?

An EpiPen® is an auto-injector, but not all auto-injectors are EpiPen. EpiPen and EpiPen Jr® are brand name epinephrine auto-injectors made by Viatris (formerly Mylan). There are other epinephrine auto-injectors on the market including:

  • AUVI-Q®
  • Adrenaclick®
  • Several generic options

SYMJEPI® is another type of epinephrine delivery device but it’s not an auto-injector. It comes as a pre-filled syringe.

How much epinephrine is in an EpiPen?

EpiPen contains 0.3 mg of epinephrine. EpiPen Jr. contains 0.15 mg of epinephrine.

Are epinephrine auto-injectors interchangeable among users?

All adult epinephrine auto-injector contain 0.3 mg of epinephrine. Auto-injectors for children contain 0.15 mg of epinephrine. However, different brands of auto-injectors should not be used interchangeably as each may have slight differences in how they are administered. Using them interchangeably could result in an error if a person is not familiar with the particular brand.

However, in an anaphylaxis emergency — if the choice is between no epinephrine or using a different brand, use the different brand. Then call 911.

When to give second dose of epinephrine?

A second dose of epinephrine should be given if symptoms persist 5-15 minutes after the first dose is administered. Sometimes symptoms reemerge between 8 and 72 hours after the first injection. These are called biphasic anaphylactic reactions.

You should call 911 or go to your nearest emergency room for medical assistance anytime you administer epinephrine.

Infographic of You Need 2. It talks about the importance of needing to carry two anaphylaxis auto-injectors because you can have a second reaction up to 15 minutes after the first.

Is epinephrine expensive?

The cost of epinephrine may vary depending on the brand prescribed and your insurance options. Epinephrine auto-injectors can be expensive — normally from around $100 to several hundred dollars. Many of the manufacturers offer copay assistance cards or discounts.

Ampules of epinephrine with a syringe and needle are much cheaper, at around $20. But they are not as user-friendly as an auto-injector and they usually take more time to administer. This could delay emergency treatment.

If you are concerned about the cost of epinephrine, talk with your healthcare provider. We also developed some tips for affording your epinephrine.

What does an epinephrine auto-injector cost?

Costs may fluctuate between brands. They may vary based on your insurance and what assistance programs you may be eligible for.

Kids hands holding two epipens in one and an inhaler in the other

What are the contraindications for epinephrine?

Epinephrine is the only medication that has no contraindications for treating anaphylaxis. This means there is no medical condition or factor that serves as a reason to withhold epinephrine. The benefit of preventing death from anaphylaxis far outweighs any potential health risks.

Healthcare providers and patients should be aware of and discuss the potential impact epinephrine may have on other medical conditions, such as heart disease. But it doesn’t matter what other medical condition is present, because anaphylaxis is a life-threatening situation and epinephrine is the only treatment for it. There is no alternative.

Can students self-carry their epinephrine auto-injectors in school?

All 50 states allow students to self-carry and administer an epinephrine auto-injector at schools. If your age-appropriate child needs to self-carry epinephrine, make sure to coordinate with the school nurse and/or teachers.

School nurse holding the arms of a young student and is facing the student. They are both smiling and relieved.

Can school nurses administer epinephrine?

The School Access to Emergency Epinephrine Act was signed into law in 2013. It permits trained school personnel including school nurses to give epinephrine to anyone having a life-threatening allergic reaction. The law also allows schools to stock emergency supplies of epinephrine in an easily accessible and secure location.

School nurses are specifically trained in both administering epinephrine and identifying allergic reactions.

Are epinephrine auto-injectors available in public places?

Thirty-five states have passed stock epinephrine entity laws for public places. In general, these laws allow — but do not require — public venues to maintain emergency supplies of epinephrine auto-injectors. Public venues may include:

  • Restaurants
  • Theme parks
  • Sports arenas
  • Shopping malls
  • Hotels
  • Day camps

Depending on the state, the laws may allow for public venues to provide anaphylaxis training to employees. They may also protect the public venue from civil liability.

How should you store an epinephrine auto-injector?

  • Store your epinephrine auto-injectors as close to room temperature as possible. Leaving them in extremely hot or cold temperatures can make the epinephrine ineffective or cause the injector to malfunction. Do not store them in your car or in a refrigerator.
  • Keep your auto-injectors out of direct sunlight. This can cause the epinephrine to oxidize (combine with oxygen, changing the makeup of the drug) and become ineffective. Oxidized epinephrine will appear dark or have solid particles in it. Epinephrine can also oxidize on its own over time, so check your device regularly to be sure the liquid inside is clear.
  • Check expiration dates. Epinephrine auto-injectors should be replaced as soon as they expire. However, if all you have is an outdated auto-injector in an emergency, use it as it may provide some benefit. Check the date on your devices regularly, including backups that may be in a school nurse’s office or at a family member’s house.

Woman in the park clutching her chest and gasping for air and is in distress

What if I am unsure if I’m having a severe asthma attack or anaphylaxis ?

The symptoms of a severe asthma attack may be similar to those of anaphylaxis. It may be difficult to recognize anaphylaxis. In both an asthma attack and an anaphylactic reaction, people may experience coughing, wheezing and shortness of breath. This is why anaphylaxis education is critical.

If you are unsure if it’s asthma or anaphylaxis, you are advised to assume it is anaphylaxis and treat symptoms immediately with epinephrine. Then call 911. Don’t use your inhaler first and see if it helps resolve symptoms. There have been numerous deaths of people who used their inhaler first and delayed giving epinephrine.

After you have administered epinephrine, you can try using your inhaler. But, again, use the epinephrine first and call 911.  

Can an epinephrine inhaler be used for anaphylaxis?

Epinephrine inhalers are available over the counter to treat symptoms of asthma. Epinephrine inhalers are not an appropriate substitute for epinephrine injections for treating anaphylaxis. The amount of epinephrine in an inhaler will not work for people having an anaphylactic reaction.

Can you use an epinephrine inhaler for bee stings?

Epinephrine inhalers should not be used to treat anaphylactic reactions from bee or insect stings. The amount of epinephrine in an inhaler will not work for people having an anaphylactic reaction.

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Reviewed by:
Bradley Chipps, MD, FACAAI, is a board-certified allergist and pediatric pulmonologist with Capital Allergy and Respiratory Disease Center in Sacramento, California. He earned his medical degree from University of Texas Medical Branch in Galveston in 1972. He is Past President of the American College of Allergy, Asthma and Immunology (ACAAI).