Anaphylaxis: Symptoms, Epinephrine, and What to Do in an Emergency
Anaphylaxis is a severe allergic reaction that can become life-threatening quickly. It may affect breathing, blood pressure, the gastrointestinal system, the skin, or several systems at once.
Common triggers
- Foods such as peanuts, tree nuts, shellfish, milk and eggs
- Medicines
- Insect stings
- Latex
- Less commonly, exercise or an unknown trigger
Symptoms can develop rapidly
Possible signs include throat tightness, trouble breathing, wheezing, swelling, widespread hives, repetitive vomiting, severe abdominal symptoms, dizziness, fainting, or signs of low blood pressure. Skin symptoms are common but are not required for anaphylaxis.
Epinephrine is the first-line treatment
If anaphylaxis is suspected and epinephrine has been prescribed, use it promptly according to the person’s allergy action plan. Epinephrine is typically given into the outer thigh.
Antihistamines do not replace epinephrine. They may help itching or hives, but they do not reliably treat the dangerous breathing or blood-pressure effects of anaphylaxis. Corticosteroids are also not a substitute for epinephrine.
Get urgent help
Follow the person’s emergency action plan and local emergency guidance. Emergency assessment is especially important if symptoms are severe, do not resolve promptly, recur, or more than one dose of epinephrine is needed.
After an episode
People who have experienced anaphylaxis may need evaluation by an allergy specialist to help identify triggers, review prevention strategies and decide whether to carry one or more epinephrine auto-injectors.
Reducing future risk
- Avoid confirmed triggers where practical.
- Carry prescribed epinephrine and know how to use it.
- Check expiration dates.
- Share an allergy action plan with family, school or caregivers when appropriate.
- Consider medical identification if advised.
Editorial sources
This article is general education and does not replace an allergy action plan or emergency medical care.
