Can Antihistamines Mask Anaphylaxis?

Published: August 29, 2016

Q: My 4-year-old son is allergic to peanuts and tree nuts, and we recently learned he also has grass allergies. Our family doctor said to give him a daily antihistamine during grass-pollen season. However, our allergist said not to, because it could mask symptoms of anaphylaxis. What should we do?

Dr. Sharma: Many children with food allergies also have hay fever. If the hay fever symptoms are bothersome, they may benefit from a daily non-sedating antihistamine.

While this gets spoken of anecdotally, there is actually no medical evidence that taking a daily non-sedating antihistamine would mask the symptoms of anaphylaxis.

The concern most allergists have about antihistamines is when they are used inappropriately to treat severe allergic reactions, or anaphylaxis, instead of epinephrine.

Antihistamines should never be used alone or in place of epinephrine for the treatment of anaphylaxis.

Antihistamines vs. Epinephrine

Where antihistamines might help is with treating symptoms of a mild allergic reaction, such as an itchy mouth, a few hives around the mouth or face, or mild itching. They cannot, however, relieve severe respiratory symptoms, gastrointestinal symptoms or anaphylactic shock.

Epinephrine is the only first-line treatment for anaphylaxis. Taking an antihistamine for severe allergic symptoms could result in a delay in administering epinephrine, and that delay increases the risk of a life-threatening reaction.

Work with your son’s allergist to develop a food allergy action plan tailored specifically to him. While an antihistamine might be appropriate to treat mild symptoms in some patients, it is important to continue monitoring to be sure the reaction does not progress to more severe symptoms of anaphylaxis.

Additionally, if there is a history of a prior severe allergic reaction, it is often advised to give epinephrine immediately, even for mild symptoms.

Dr. Sharma is an allergist, clinical researcher and associate professor of pediatrics. He is Chief of the Division of Allergy and Immunology at Children’s National Medical Center in Washington D.C. and Director of the Food Allergy Program. Questions submitted will be considered for answer.

Related: All About Epinephrine: What It Does, What if It Gets Hot or Cold

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