My WebMD Sign In, Sign Up

Ask Your Question

WebMD Answers

120 Characters remaining
120 Characters remaining
  • First, try and keep your question as short as possible.
  • Include specific words that will help us identify questions that may already have your answer.
  • If you don't find your answer, you can post your question to WebMD Experts and Contributors.


Posted: | Report This Report Question |

Answers From Experts & Organizations (1)

7,995 Answers
375,352 Helpful Votes

Anaphylaxis is a sudden, severe allergic reaction that occurs when you are exposed to a substance that your body was sensitized to during a previous exposure.

The life-threatening reaction causes a sudden release of chemicals, including histamines, from cells in the blood and the body's tissues. These chemicals dilate the blood vessels, lowering blood pressure, and they cause the blood vessels to leak fluid, leading to hives and swelling, especially around the face and throat. The chemicals also act on the lungs, causing an asthmatic reaction -- that is, causing the lung's airways to constrict, thus making breathing very difficult.

In some cases, anaphylaxis may have mild symptoms, causing only hives and itching. But it can be deadly. Blood pressure can drop severely, leading to loss of consciousness. Swelling of the throat and airways can cause difficulty breathing, speaking, and swallowing. Anaphylaxis is a medical emergency.

This answer should not be considered medical advice...down arrowThis answer should not be considered medical advice and should not take the place of a doctor’s visit. Please see the bottom of the page for more information or visit our Terms and Conditions.up arrow

| Report This Report Answer
Archived: March 20, 2014

Was this helpful?


Thanks for your feedback.

492 of 512 found this helpful
Read the Original Article: Understanding Anaphylaxis - the Basics