Epinephrine (EpiPen, Auvi-Q): Uses, Dosing, Side Effects

Epinephrine (also called adrenaline) is the first-line emergency medicine for a severe allergic reaction, known as anaphylaxis. It comes as a pre-filled auto-injector such as EpiPen or Auvi-Q, which anyone can use in seconds, through clothing, into the middle of the outer thigh. The single most important thing to know is timing: when anaphylaxis starts, the injection should be given right away, and emergency services should be called after it, not instead of it.

This guide explains what epinephrine is, how the auto-injectors differ, the weight-based doses on the labels, how to use one step by step, what side effects are normal, and the questions families ask most. If you are reading this because someone is having a reaction right now, stop reading, use the auto-injector, and call 911.

This is general information based on FDA labeling and manufacturer instructions, not medical advice. Your doctor should prescribe the device and dose for you or your child and go over how to use it.

Epinephrine at a glance

What it is	A non-selective alpha and beta-adrenergic receptor agonist, a natural stress hormone in medicine form
FDA-approved use	Emergency treatment of allergic reactions (Type I), including anaphylaxis
Common auto-injectors	EpiPen and EpiPen Jr, Auvi-Q, and generic versions
Where to inject	Middle of the outer thigh, through clothing if needed
Second dose	May be given with a second auto-injector starting 5 minutes after the first if there is no improvement or symptoms worsen
After using it	Get emergency medical care
Contraindications	None listed on the auto-injector labels, because the risk of untreated anaphylaxis is greater

What epinephrine does

Epinephrine is a version of the hormone your body releases under stress. In an allergic emergency, the immune system releases chemicals that widen blood vessels, make them leak, tighten the airways, and swell the tissues of the face and throat. Blood pressure can fall dangerously.

Epinephrine acts on alpha and beta receptors in the body, which is why the label calls it a non-selective alpha and beta-adrenergic agonist. Acting on these receptors it narrows blood vessels, which raises blood pressure and reduces swelling, relaxes airway muscles so breathing is easier, and increases the force of the heartbeat. It works within minutes, and its effect is short, which is why a second dose may be needed.

No other common medicine does all of this. Antihistamines such as Benadryl can ease itching and hives, but they do not reverse a falling blood pressure or a closing airway. For a fuller explanation, see our guide to EpiPen vs Benadryl.

Recognizing anaphylaxis

Anaphylaxis usually involves more than one part of the body and comes on within minutes, sometimes up to a couple of hours, after contact with a trigger. Signs include:

Hives, widespread itching, or flushing
Swelling of the lips, tongue, face, or throat
Trouble breathing, wheezing, or a tight throat, hoarse voice, or trouble swallowing
Vomiting, severe stomach cramps, or diarrhea
Dizziness, fainting, a weak pulse, or pale, clammy skin
A sense of doom or sudden confusion

Common triggers are foods (peanuts, tree nuts, shellfish, milk, egg), insect stings, medicines, and latex. Sometimes no trigger is found. If someone at risk shows serious symptoms after a likely trigger, treat it as anaphylaxis. The risk of giving epinephrine when it turns out not to be needed is far smaller than the risk of withholding it when it is.

The auto-injectors compared

The two best-known products deliver the same medicine but differ in design and dose options.

	EpiPen / EpiPen Jr	Auvi-Q
Doses	0.3 mg (EpiPen) and 0.15 mg (EpiPen Jr)	0.3 mg, 0.15 mg, and 0.1 mg
Smallest patient	Label dosing starts at 15 kg (33 lb)	Approved for patients weighing 7.5 kg (16.5 lb) or more
Guidance	Written instructions on the device	Built-in electronic voice instructions, beeps, and LED lights
Where to inject	Outer thigh only; not the buttock	Middle of the outer thigh only
Second dose	Single-use device; a second device is used if needed	Second auto-injector starting 5 minutes after the first

The Auvi-Q 0.1 mg dose is the notable difference. It was designed for infants and toddlers who weigh between about 16.5 and 33 pounds, a range the other devices do not cover with a label dose. Auvi-Q also has built-in spoken instructions, which can help a frightened caregiver who has never used one.

Generic and other-brand epinephrine auto-injectors are available as well. They work the same way, but the steps to trigger them differ slightly, so learn the exact device you have been prescribed.

Dosing by weight

Epinephrine auto-injectors are dosed by body weight. The Auvi-Q label lists:

Patient weight	Auvi-Q dose
30 kg (66 lb) or more	0.3 mg
15 kg to under 30 kg (33 to 66 lb)	0.15 mg
7.5 kg to under 15 kg (16.5 to 33 lb)	0.1 mg

The EpiPen labels use the same logic for the two doses they carry: 0.3 mg for patients 30 kg or more and EpiPen Jr 0.15 mg for patients 15 to 30 kg.

Children grow, so the prescribed dose may need to change over time. Ask the doctor to review the dose at each visit. Because the doses are fixed inside the device, the label for EpiPen notes that a clinician may consider other forms of injectable epinephrine for patients who need a dose the auto-injector cannot deliver.

Do not try to adjust an auto-injector dose yourself or use someone else’s. Have the prescribed dose checked against current weight.

How to use an epinephrine auto-injector

Read the instructions for your specific device ahead of time, and practice with the trainer device that comes with it. The steps below reflect the Auvi-Q instructions for use and the general pattern for others.

Get the device and stay calm. Remove it from its case. Have a second one within reach.
Remove the safety piece. On Auvi-Q, pull off the red safety guard. It fits tightly, so pull firmly. Do not touch the base of the device, which is where the needle comes out, to lower the chance of an accidental injection.
Place it on the outer thigh. Put the black end against the middle of the outer thigh. It can go through clothing if necessary. Inject only into the middle of the outer thigh, never the buttock. The EpiPen label states injection into the buttock may not treat anaphylaxis effectively.
Press firmly and hold. Push until you hear a click and a hiss, then hold in place for 2 seconds (Auvi-Q). Follow the hold time printed on your specific device.
Call 911. Say the person is having anaphylaxis and has used epinephrine.
Lay the person down. Raise the legs unless breathing is easier sitting up or the person is vomiting. Do not make them stand or walk.
Give a second dose if needed. If there is no improvement, or symptoms get worse, a second dose may be given with a second auto-injector starting 5 minutes after the first.
Go to the emergency department. Even if symptoms improve. A reaction can return hours later, and the person needs to be watched and assessed.

The Auvi-Q instructions add that patients should always carry two devices, and that if more than two doses are needed for a single episode, any further doses must be given by a healthcare provider.

If someone else gets injected by accident

Because the needle can come out of the base, accidental injection (often into a finger or thumb) can happen, especially when a device is used on a struggling child. The Auvi-Q instructions say to get medical help right away if it happens.

Side effects

Epinephrine is a stress hormone, so its common effects feel like a stress response. They are usually short-lived:

Fast or pounding heartbeat
Shakiness or tremor
Anxiety or restlessness
Dizziness or lightheadedness
Sweating
Pale skin, headache, or nausea

These effects pass, and they are far less dangerous than untreated anaphylaxis. That is why the auto-injector labels list no absolute contraindications. Caution is still important in people with heart disease, high blood pressure, thyroid disease, or diabetes, and some medicines can affect how epinephrine works or how the body responds. Tell the prescriber about your full medical history so the plan is made with your risks in mind.

Products containing sodium metabisulfite, a sulfite, carry a label warning for people with sulfite sensitivity. That warning is not a reason to withhold epinephrine in an emergency.

Rarely, accidental injection into a finger, hand, or foot can reduce blood flow to that area. It needs prompt medical attention.

Who should carry epinephrine

A doctor, usually an allergist, prescribes an auto-injector to people who have had a serious allergic reaction or who are at high risk of one. This includes people with severe food allergies, insect sting allergy, or allergies to certain medicines, as well as some with previous anaphylaxis of unknown cause.

Practical habits that help:

Carry two devices wherever you go, as the manufacturer recommends. Keep them with you, not in a car or locker.
Make an action plan. Ask for a written anaphylaxis action plan and share copies with schools, childcare, relatives, and coaches.
Train the people around you. Practice with trainer devices so that someone else can act if you cannot.
Check expiry dates and the liquid. Replace devices before they expire. Do not use one if the liquid looks discolored or contains particles. Follow the storage instructions in your package insert.
Wear medical ID if you have serious allergies.
Learn your triggers and review the plan with your allergist regularly.

Epinephrine vials and hospital use

Auto-injectors are for self or caregiver use. Hospitals and ambulances use epinephrine in vials and syringes, drawing up a dose according to the patient, and sometimes give it through an IV in severe cases. Vial products such as Adrenalin are also labeled for certain other hospital uses. Those are given by trained staff and are not the same as carrying an auto-injector.

Myths that delay treatment

“I’ll wait and see if it gets worse.” Anaphylaxis can move fast, and the reasons to give epinephrine early are stronger than the reasons to wait. If breathing, throat, or circulation symptoms appear after a likely trigger, that is the moment to inject.

“Epinephrine is too dangerous for the heart.” It does speed the heart and raise blood pressure, and people with heart conditions should discuss their plan with their doctor in advance. But in a life-threatening allergic reaction, the danger of untreated anaphylaxis is greater, which is why the labels list no contraindications.

“An antihistamine is enough.” Antihistamines treat itching and hives. They do not fix falling blood pressure or a closing airway. They may be used in addition to epinephrine after the injection, never in place of it.

“If the symptoms go away, I’m fine.” Epinephrine wears off quickly, and the original reaction can return, sometimes hours later. That is why every use of epinephrine means going to the emergency department.

“I’ll use it only for food reactions.” Insect stings, medications, and latex can also cause anaphylaxis, and your action plan should cover all of your known triggers.

Return of symptoms after treatment

Some people improve after epinephrine, then have symptoms come back hours later even without further exposure. Doctors call this a biphasic reaction. It is one of the main reasons for observation after treatment. Staff decide how long to keep someone based on how severe the reaction was, how many doses were needed, and the person’s history. Do not leave against advice just because you feel better.

Preparing for school, travel, and everyday life

Carrying the device is only part of preparedness. The rest is planning.

Schools and childcare. Give staff a written action plan, the medication with its pharmacy label, and a way to reach you. Many states allow students to carry their own auto-injector; ask the school what its policy is.
Restaurants and shared meals. Tell the kitchen about the allergy every time, read ingredient labels each time (recipes change), and be careful about cross-contact from shared utensils and surfaces.
Travel. Keep the auto-injectors in your carry-on with the prescription label, not in checked luggage. Avoid leaving them in a hot car or in freezing conditions, and follow the storage temperatures in your package insert. Carry a copy of your action plan and a letter from your doctor.
Insect season. Tell friends and family where your device is kept when you are outdoors.
Sports and camps. Coaches and camp staff should know your plan and where the medicine is.

The Auvi-Q materials advise always carrying two devices, and that is a reasonable habit for any auto-injector: the second is there if the first fails or symptoms come back before help arrives.

Cost and getting a prescription

Epinephrine auto-injectors are prescription-only, and price has been a concern for families for years. Options that can help include generic auto-injectors, manufacturer savings programs, and asking about alternative products when one is costly. Ask your prescriber or pharmacist, and check your insurance plan, since coverage and what you pay differ widely. Do not skip refilling an expired device because of cost without first asking about ways to lower it.

Frequently asked questions

Can I use an epinephrine auto-injector if I am not sure it is anaphylaxis?

Yes. If someone at risk has serious symptoms after a likely trigger, such as trouble breathing, throat swelling, or faintness, using epinephrine is the safer choice. The side effects are short-lived, while anaphylaxis can become life-threatening within minutes.

Do I still need to call 911 after using it?

Yes. Epinephrine’s effect is short and symptoms can return. The person needs emergency assessment and observation every time.

Where do I inject it?

In the middle of the outer thigh, through clothing if necessary. Do not inject into the buttock, and do not touch the needle end of the device.

How long should I wait before a second dose?

The Auvi-Q label says a second dose may be given with a second auto-injector starting 5 minutes after the first if symptoms have not improved or have worsened. If more than two doses are needed, a healthcare provider must give them.

Is Auvi-Q different from EpiPen?

Both deliver epinephrine. Auvi-Q has voice instructions and offers a 0.1 mg dose for infants and toddlers who weigh 7.5 kg (16.5 lb) or more. EpiPen comes in 0.3 mg and 0.15 mg doses.

Is Benadryl a substitute for epinephrine?

No. Antihistamines can ease itching and hives but do not treat airway swelling or low blood pressure. Epinephrine is the first-line treatment for anaphylaxis.

Can I give epinephrine to a child?

Yes, if prescribed and dosed correctly for their weight. Auvi-Q is labeled for patients weighing 7.5 kg (16.5 lb) or more, and the dose depends on weight. Ask your child’s doctor to recheck the dose as they grow.

Does the injection hurt?

There is a brief sting and pressure at the injection site. The needle is short and the injection takes about two seconds. The discomfort is small compared with the reaction it treats.

What if the auto-injector is expired?

Replace it before the expiry date. If someone is having anaphylaxis and the only device on hand is expired, call 911 immediately and tell the dispatcher, who can advise you while help is on the way.