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What is anaphylaxis? — Anaphylaxis is the term doctors use to describe a serious allergic reaction. It can happen very quickly and can cause death. Anaphylaxis can happen after a person:
Eats a food he or she is allergic to
Takes a medicine he or she is allergic to
Is stung by an insect he or she is allergic to
Touches something made out of latex if he or she is allergic to latex
Other triggers can also cause anaphylaxis.
You might know if you are allergic to something. But you can also have anaphylaxis even if you don't know you have an allergy.
What are the symptoms of anaphylaxis? — Anaphylaxis can involve one or more parts of the body. The most common symptoms are:
Hives – Raised, red patches of skin that are very itchy (picture 1)
Angioedema – A condition that causes puffiness, usually of the face, eyelids, ears, mouth, hands, or feet
Other symptoms can include:
Redness or itching of the skin (without hives)
Swelling or itching of the eyes
Runny nose or swelling of the tongue
Trouble breathing, wheezing, or a change in your voice
Throwing up or having diarrhea
Feeling dizzy or passing out
With anaphylaxis, you can get very sick, very quickly. Your symptoms can also change. You might first get hives on your skin. Soon after that, you might throw up or have trouble breathing. Each time you have anaphylaxis, you can have different symptoms. Symptoms also differ from person to person.
The symptoms you have with anaphylaxis can be worse if you:
Have asthma
Have other health problems such as lung or heart disease
How is anaphylaxis treated? — There are treatments that can help reduce anaphylaxis symptoms quickly. The best treatment is a medicine called "epinephrine." Epinephrine comes in a shot. Ambulance crews and doctors can give it.
People who have had anaphylaxis before often get a prescription for a device called an "autoinjector" (for example, the EpiPen). This device has a shot of epinephrine that you can give yourself. If you have an autoinjector, you should keep it with you at all times. Use it right away any time you think you are having anaphylaxis. After you use the autoinjector, call for an ambulance (in the US and Canada, dial 9-1-1). That's because the symptoms might come back and you might need more treatment in the hospital. A doctor or nurse will also watch you to make sure your symptoms do not come back.
Should I see a doctor or nurse? — Yes. If you think you have anaphylaxis, act fast! If you have an epinephrine auto-injector, use it right away. Then call for an ambulance (in the US and Canada, dial 9-1-1). Do not try to get yourself to the hospital because you might pass out or stop breathing on the way there. Also, calling an ambulance is usually the fastest way to get help.
Is there anything I can do to prevent anaphylaxis again? — Yes. If you have had anaphylaxis, you should talk with your doctor or nurse. If needed, your doctor can do tests to find out what you are allergic to.
Your doctor can help you make a plan to prevent future anaphylaxis. As part of your plan, you can:
Learn about the symptoms of anaphylaxis so you will know when to get help
Have an epinephrine auto-injector with you at all times
Avoid foods, medicines, or insects you are allergic to
Wear a medical bracelet to let others know about your allergy
What will my life be like? — Many people who have had anaphylaxis are able to live normal lives. But you might need to make some changes in your life. You will need to avoid the things that can cause you to have anaphylaxis. You might need to carry medicine with you in case you have an allergic reaction.
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 15336 Version 12.0
Release: 28.2.2 - C28.105
© 2020 UpToDate, Inc. and/or its affiliates. All rights reserved.

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