Severe allergic reactions


Know the signs

Most allergic reactions are mild, but some can be severe, like anaphylactic shock, which is a rare but life-threatening reaction to an allergen.

Call 911 or go to the nearest emergency room if you have trouble breathing, you have swelling all over your body, or you think you will pass out. Call your doctor immediately if you suspect that you are having a severe allergic reaction.

Severe allergic reactions can include:

  • hives (an itchy, reddish rash)
  • a severe drop in blood pressure
  • dizziness or light-headedness
  • abdominal cramps
  • nausea and vomiting
  • diarrhea
  • swelling of your mouth, nose, and throat, so that you have difficulty breathing
  • a feeling of doom

If you have severe food, drug, or insect allergies, you may want to keep an Epi-Pen with you at all times. Ask your doctor or pharmacist to show you how to use it during an allergy emergency, and train other people in your home on what to do.

Reviewed by: Patricia McNally, MD, November 2018