Epinephrine (auto-injector)

Introduction

Written by Patricia Weiser, PharmD
Medically reviewed by Victor Nguyen, PharmD, MBA
Updated on July 27, 2023

Epinephrine (ep i NEF rin) is a generic medication prescribed for severe allergic reaction. Epinephrine belongs to a group of drugs called alpha-adrenergic and beta-adrenergic receptor agonists.

The Food and Drug Administration (FDA) has approved epinephrine to:

• treat severe allergic reactions, including anaphylaxis, in adults and children
• increase blood pressure in adults experiencing low blood pressure due to septic shock

These approved uses differ based on the form of epinephrine your doctor prescribes.

Common questions about epinephrine

Below you’ll find answers to a few commonly asked questions about epinephrine.

How does epinephrine compare with norepinephrine?

Epinephrine and norepinephrine are similar drugs. They’re both used to increase blood pressure, but in different situations. Epinephrine is used to increase blood pressure in adults experiencing septic shock (a severe reaction to an infection).* Norepinephrine is used to increase blood pressure in adults with extremely low blood pressure.

Epinephrine and norepinephrine are also natural chemical messengers in your body. They stimulate some of the same receptors (binding sites) in your body, but to different degrees. As a result, norepinephrine mainly affects your heart and arteries (a type of blood vessel). And epinephrine has a more widespread effect on your entire body.

To learn more about how epinephrine compares with norepinephrine, talk with your doctor or pharmacist.

* For details about epinephrine’s other uses, see the “Uses of epinephrine” section.

Is epinephrine a hormone?

Yes, epinephrine is a hormone. It’s the same thing as adrenaline, also called the “fight-or-flight” hormone. The adrenal glands naturally release epinephrine to help your body respond to dangerous or stressful situations. Adrenaline increases your heart rate and blood pressure. This boosts the flow of blood and oxygen to your body. It also triggers the release of blood sugar to provide a rush of energy.

As a drug, epinephrine is used to treat severe allergic reaction. It’s also used to increase blood pressure in adults with septic shock (a severe reaction to an infection). Similar to its role as a hormone, the drug is used to help the body respond to life threatening conditions.

If you have questions about hormones and epinephrine, talk with your doctor or pharmacist.

How does epinephrine work? And how long does it take to start working?

Epinephrine works by attaching to alpha- and beta-adrenergic receptors (binding sites) throughout your body. This causes an increase in blood pressure and relaxation of muscles in your airway. Epinephrine also causes certain blood vessels to narrow, which increases blood pressure as well.

These actions by epinephrine help stop or reverse the symptoms of severe allergic reaction. Epinephrine also increases blood pressure in adults experiencing low blood pressure due to septic shock (a severe reaction to an infection).  

Epinephrine begins working immediately after a dose is given.

If you’d like to know more about what to expect with epinephrine treatment, talk with your doctor or pharmacist.

Uses of epinephrine

The Food and Drug Administration (FDA) approves prescription drugs such as epinephrine for certain conditions. Approved uses for epinephrine are described below. These uses differ based on the form of epinephrine prescribed.

Use for severe allergic reaction

Doctors may prescribe epinephrine injection to treat severe allergic reaction, including anaphylaxis. The injection is given into the muscle or under the skin. Epinephrine is used for this purpose in children and adults. It’s usually prescribed as a short-term treatment.

During a severe allergic reaction, a person has sudden, intense symptoms within minutes after being exposed to an allergen. (An allergen is a substance that produces an allergic reaction). Symptoms may include:

• difficulty breathing
• swelling of the face, tongue, lips, or throat
• hives
• low pulse
• nausea

Note: If you have a severe allergic reaction and inject epinephrine, you or someone else should immediately call 911 (or a local emergency number). Or you should go to the nearest hospital. Severe allergic reaction may require medical care even after epinephrine is given.

Use for low blood pressure

Doctors may prescribe epinephrine intravenous (IV) infusion (an injection given into your vein over time). This form of epinephrine is used for treating low blood pressure due to septic shock. It’s used for this purpose in adults and is usually prescribed as a short-term treatment.

With septic shock, you experience a sudden drop in blood pressure due to sepsis. Sepsis is a serious reaction to an infection. In septic shock, a person’s blood pressure may become so low that it becomes life threatening.

Other symptoms of severe septic shock include:

• mental confusion
• difficulty breathing
• failure of multiple organs
• cyanosis (bluish fingers, toes, or lips)

Side effects of epinephrine

Epinephrine may cause mild or serious side effects. More common mild side effects of epinephrine and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about epinephrine’s side effects, ask your doctor or pharmacist. You can also refer to the prescribing information for epinephrine listed in the “Resources” section.

Mild side effects

More common mild side effects reported with some forms of epinephrine are listed below. These side effects may differ based on the form of epinephrine you’re prescribed.

This article doesn’t include all possible mild side effects of the drug. To learn more about epinephrine’s side effects based on the form, refer to the prescribing information for epinephrine listed in the “Resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Mild side effects of epinephrine injection given into the muscle or under the skin include:

• anxiety
• nausea
• dizziness
• headache
• mild allergic reaction*

Mild side effects of epinephrine injection given in the vein include:

• fast heart rate
• chest pain
• headache
• tremor (shaking)
• mild allergic reaction*

* For details about this side effect, see the “Interactions and warnings for epinephrine” section.

Serious side effects

Serious side effects of epinephrine are listed below. These side effects may differ based on the form of epinephrine you’re prescribed.

This article doesn’t include all possible serious side effects of the drug. To learn more about epinephrine’s side effects based on the form, refer to the prescribing information for epinephrine listed in the “Resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, epinephrine’s serious side effects include:

• serious infection at the injection site
• heart problems, such as arrhythmia
• high blood pressure
• kidney problems
• lung problems, such as pulmonary edema
• reduced blood flow or tissue damage around the injection site*
• severe allergic reaction†

* This can occur if the drug is injected incorrectly or if the drug leaks out of a vein into surrounding tissue.
† For details about this side effect, see the “Interactions and warnings for epinephrine” section.

Interactions and warnings for epinephrine

Below you’ll find information about epinephrine’s possible interactions and warnings.

Interactions of epinephrine

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you use epinephrine, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for epinephrine” section below.

Warnings for epinephrine

Epinephrine should be used cautiously by certain people.

Epinephrine could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether epinephrine is a safe option for you. These warnings may differ based on the form of epinephrine you’re prescribed.

Ask your doctor about specific warnings for epinephrine, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Epinephrine can cause an allergic reaction in some people. Severe allergic reactions are rare but possible. (Epinephrine is also used to treat severe allergic reaction. For details, see the “Uses of epinephrine” section.)

If you’ve had an allergic reaction to epinephrine or any of its ingredients, your doctor will likely not prescribe epinephrine. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to epinephrine, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of epinephrine

If you inject epinephrine, you should not inject more than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve used too much epinephrine, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and epinephrine

Information about epinephrine and pregnancy and breastfeeding is described below.

Epinephrine and pregnancy

In general, epinephrine is considered safe to use during pregnancy for severe allergic reaction. That said, ask your doctor about whether they feel it’s safe for you.

There are risks to using epinephrine during pregnancy for low blood pressure due to septic shock. But there are more severe risks if this condition is not treated. In fact, this condition is life threatening. (Epinephrine is used for treating low blood pressure due to septic shock. For details, see the “Uses of epinephrine” section.) So your doctor will likely prescribe epinephrine to treat these conditions even if you’re pregnant.

Talk with your doctor if you have questions about epinephrine use during pregnancy.

Epinephrine and breastfeeding

There may be risks to using epinephrine while breastfeeding.

But there are worse risks if a severe allergic reaction or low blood pressure due to septic shock is not treated. In fact, these conditions are life threatening. (Epinephrine is used to treat these conditions. For details, see the “Uses of epinephrine” section.) So your doctor will likely prescribe epinephrine to treat these conditions even if you’re breastfeeding.

Talk with your doctor if you have questions about breastfeeding your child after you’ve used epinephrine.

What to ask your doctor

Let your doctor know if you have questions about epinephrine or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• How many doses of epinephrine should I have available?
• What should I do with unused epinephrine that has expired?
• How much exposure to my allergen will require me to need epinephrine?
• Should I continue taking my other medications if I need to use a dose of epinephrine?

Resources

• Epinephrine injection USP, 1 mg/mL syringe, for intravenous use. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/7499cbca-b8fe-4fc3-a318-13859ab989a7/spl-doc
• Epinephrine injection, 0.3 mg, for intramuscular or subcutaneous use. Epinephrine injection, 0.15 mg, for intramuscular or subcutaneous use. (2021). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/de4916c5-bdc8-4da9-a857-a319882a831a/spl-doc
• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks 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.