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Serious Allergic Reactions (Anaphylaxis)

What Is Anaphylaxis?

Anaphylaxis is a severe allergic reaction that can be life-threatening. Things that can cause allergic reactions are called allergens.

Anaphylaxis (pronounced: an-eh-fih-LAK-siss) most often happens during allergic reactions to:

  • foods
  • insect stings
  • medicines
  • latex

Anaphylaxis can be scary. But being prepared will help you treat a reaction quickly.

What Are the Signs & Symptoms of Anaphylaxis?

Severe allergic reactions can cause:

  • trouble breathing
  • throat tightness or feeling like the throat or airways are closing
  • hoarseness or trouble speaking
  • wheezing or cough
  • nasal stuffiness
  • nausea, belly pain, vomiting, and/or diarrhea
  • trouble swallowing or drooling
  • low blood pressure
  • skin itching, redness, or swelling
  • hives
  • a feeling like something bad is about to happen
  • passing out

Anaphylaxis can cause different symptoms at different times. An allergic reaction is considered anaphylaxis if someone has:

  • any severe symptoms, such as trouble breathing, repeated vomiting, passing out, or throat tightness
  • two or more mild symptoms, such as hives and vomiting or coughing and swelling

A person with symptoms of anaphylaxis needs treatment right away.

How Is Anaphylaxis Treated?

Someone with anaphylaxis needs help right away. The reaction can get worse very quickly. So doctors usually want people with allergies to carry injectable medicine called epinephrine. Epinephrine enters the bloodstream and works quickly against serious allergy symptoms.

Doctors prescribe epinephrine auto injectors. These should always be with the person with allergies, including at school, sports, jobs, and other activities. The auto injector is small and easy to use.

If you're prescribed epinephrine auto injectors, the doctor will show you how to use them. Always have two auto injectors with you in case one doesn't work or you need a second dose.

Your doctor also might instruct you to take antihistamines in some cases. But always treat a serious reaction with epinephrine. Never use antihistamines instead of epinephrine in serious reactions.

What to Do if You Have Anaphylaxis

Give yourself epinephrine right away if you start to:

  • have trouble breathing
  • feel tightness in your throat
  • feel faint
  • have two or more milder allergic symptoms together (like hives with coughing)

Don't try to use an inhaler or antihistamine and wait to see what happens. Go straight for the epinephrine! Time matters during anaphylaxis.

If you have signs of a serious allergic reaction:

  1. Use the epinephrine auto-injector right away. Then call 911.
  2. Lay down with your legs raised while you wait for the ambulance.
  3. Go to the emergency room, even if symptoms improve after epinephrine. You must be under medical supervision for several hours. This is because a second wave of serious symptoms (called a biphasic reaction) can happen. You can get more treatment at the emergency room, if you need it.

What Else Should I Know?

Being prepared can help you stay safe:

  • Carry two epinephrine auto injectors with you at all times. Epinephrine can be a lifesaver.
  • Avoid the things you are allergic to.
  • Let friends, teachers, and coaches know about your allergies and how they can help you if you have a reaction.

Reviewed by: Hillary B. Gordon, MD
Date Reviewed: Jan 1, 2022

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