Why do some people get severe allergic reactions to vaccines or medicines?
Quick Answer
A severe allergic reaction, or anaphylaxis, happens when the immune system overreacts quickly to a substance and releases chemicals that affect breathing and blood pressure. It is rare but can be life-threatening and needs emergency treatment.
The Full Story
Anaphylaxis is a rapid, potentially life-threatening allergic reaction that can involve the skin, lungs, and circulatory system. It is caused by immune mediators such as histamine being released suddenly, which can lead to swelling, wheezing, and dangerously low blood pressure. In vaccine programs, anaphylaxis is rare, which is why people are usually observed for a short period after vaccination. Immediate treatment with epinephrine is critical. Medical systems screen for prior allergies and keep emergency equipment available whenever vaccines are administered.
Key Facts
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"Why can an allergy become an emergency? The immune system can overreact fast."
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