What is anaphylactic reaction?

Anaphylactic Reaction
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Anaphylactic reaction: Overview

A bad allergic reaction can affect your whole body. Doctors call it an anaphylactic reaction. Your immune system may have reacted to food or medicine. Or maybe you had an insect bite or sting. This kind of reaction can happen the first time you come into contact with a substance. Or it may take many times before a substance causes a problem.

You need to get help right away if your body reacts like this again.


Anaphylaxis (say "ann-uh-fuh-LAK-suss") is a severe allergic reaction that affects the entire body (systemic). It can occur within a few seconds or minutes after a person is exposed to a substance (allergen or antigen).

Symptoms and signs of a severe allergic reaction may include:

  • Itching.
  • Raised, red bumps on the skin (hives or wheals).
  • Wheezing or difficulty breathing.
  • Rapid swelling, either in one area or over the entire body. Swelling is most serious when it involves the lips, tongue, mouth, or throat and interferes with breathing.
  • Belly pain or cramps.
  • Nausea, vomiting, or diarrhea.
  • Low blood pressure, shock, and unconsciousness.

The sooner symptoms occur after exposure to the substance, the more severe the anaphylactic reaction is likely to be. An anaphylactic reaction may occur with the first exposure to an allergen, with every exposure, or after several exposures. An anaphylactic reaction can be life-threatening and is a medical emergency. Emergency care is always needed for an anaphylactic reaction.

How can you care for an anaphylactic reaction?

  • If your doctor has prescribed medicine, such as an antihistamine, take it exactly as directed. Call your doctor if you think you are having a problem with your medicine.
  • Learn all you can about your allergies. You may be able to avoid a severe response when you do or don't do certain things. For instance, you can check food or drug labels for contents that might cause problems.
  • Your doctor may prescribe a shot of epinephrine to carry with you in case you have a severe reaction. Learn how to give yourself the shot. Keep it with you at all times. Make sure it has not expired.
  • Wear medical alert jewelry that lists your allergies. You can buy this at most drugstores.
  • Teach people around you about your allergies. Tell them what you need to avoid. Teach them what to do if you have a reaction.
  • Before you take any medicine, tell your doctor if you have had a bad response to any medicines in the past.

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The content above contains general health information provided by Healthwise, Incorporated, and reviewed by its medical experts. This content should not replace the advice of your healthcare provider. Not all treatments or services described are offered as services by us. For recommended treatments, please consult your healthcare provider.

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