What causes anaphylaxis?

Anaphylaxis is caused by a severe allergic reaction that occurs after an exposure to a substance that a person's immune system has been sensitized to previously. The allergen causes the sensitized immune system to release histamine and other chemicals from different tissues in the body, which then causes the symptoms that occur. Common allergens include medications such as penicillin, peanuts, tree nuts, wheat, fish, shellfish, milk, eggs, and insect stings from bees, yellow jackets, wasps, hornets, and fire ants. 

Anaphylaxis can be triggered by allergens in insect stings, food, certain medications or other substances.

Continue Learning about Allergies



About one out of five Americans suffers from allergies. An allergy is an exaggerated response from the immune system to a substance such as dust, pollen, pet dander or mold. Other common triggers include foods such as peanuts and ...

milk; insect bites; and certain ingredients in cosmetics and jewelry. Allergies can cause anything from rashes and hives to itchy eyes, sneezing, coughing, diarrhea, vomiting, and wheezing.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.