What is anaphylaxis?

Anaphylaxis (say "anna-full-ax-iss") is a life-threatening allergic reaction. It starts soon after you are exposed to something you are severely allergic to. You may have swelling, itching or a rash. Some people have trouble breathing, a tight feeling in their chest or dizziness. Some people feel anxious. Other people have stomach cramps, nausea or diarrhea. Some people lose consciousness ("pass out").

What causes anaphylaxis?

Many things can cause anaphylaxis. Some common causes include the following:

  • Foods, such as shellfish, nuts, peanuts, eggs and fruits
  • Medicines, such as antibiotics, aspirin, over-the-counter pain relievers, allergy shots and contrast dye for radiologic procedures
  • Latex or rubber found in surgical gloves, medical supplies and many products in your home
  • Insect stings, especially from bees, wasps, hornets, yellow jackets, sawflies and fire ants

How do I prevent anaphylaxis?

The following are some ways to help prevent a reaction:
  • If you have had anaphylaxis, make sure your doctor and dentist know so that it is recorded on your medical chart. Tell them what you are allergic to, if you know.
  • If you are allergic to insect stings, wear protective clothing and insect repellent when you're outside.
  • Avoid handling or eating foods you are allergic to. Even tiny amounts mixed by accident into your food can cause a reaction. Read the ingredient list on any packaged foods you are going to eat.
  • Wear or carry a medical alert bracelet, necklace or keychain that warns emergency medical technicians (EMTs) and doctors that you are at risk for anaphylaxis.
  • Ask your doctor if you need desensitization shots.
  • Ask your doctor if there are other things you also might be allergic to.
If you are at risk of anaphylaxis, keep an emergency anaphylaxis kit with you at all times. Make sure the people around you, such as your family and friends, know how to use it.

What is in an emergency anaphylaxis kit?

If you have a severe allergic reaction, you might need medical help right away. An emergency anaphylaxis kit contains medicine to counteract your allergic reaction. This medicine is usually a drug called epinephrine that you inject into your arm or leg (or have a friend inject). Your doctor will prescribe a kit with the right dose of medicine and will teach you how to use it. Make sure your family, friends and coworkers also know how to use the kit. Sometimes your doctor will tell you to keep an antihistamine, such as diphenhydramine (one brand name: Benadryl), in the kit too.

How do I treat anaphylaxis when I am having an allergic reaction?

Call 911 to get emergency medical help, even if you do not feel very sick. Get your anaphylaxis kit. Inject yourself with epinephrine or have someone else do it. If your doctor has recommended it, take an antihistamine. If you stop breathing, you may need someone to perform CPR (cardiopulmonary resuscitation) on you until help arrives.

What can I expect after anaphylaxis?

You should recover completely with treatment. Most people live a normal, full life. You can get back to your normal activities once you are feeling better. However, you should have someone stay with you for 24 hours after anaphylaxis to make sure another attack does not happen.

More Information

For more information talk to your doctor.

Other Organizations


Written by editorial staff.

A Practical Guide to Anaphylaxis by TW Tang, M.D. (American Family Physician October 1, 2003,

Reviewed/Updated: 12/06
Created: 11/04