Yes, You Actually Can Be Allergic to Exercise—Here’s How, According to an MD

Even under the best circumstances, exercising can be arduous—point-blank. It’s generally uncomfortable, and if you go too hard, you can pass out, throw up, or get injured. Though most people might find that discomfort is their biggest workout adversary, exercise can also trigger an allergic reaction in rare cases. This allergic reaction is called exercise-induced anaphylaxis (EIA), and, though uncommon, it’s a real and potentially dangerous condition.

What is exercise-induced anaphylaxis

Before we break down exercise-induced anaphylaxis, let’s talk about allergies. An allergy is a complex immune response that impacts numerous body processes, says Ratika Gupta, MD, board-certified allergist and immunologist. For instance, an allergy can manifest as more mucus in your sinuses. It can trigger hives on your skin or cause reactions like eye swelling and a host of other symptoms.

In some cases, allergies can also cause anaphylaxis, a term used to describe a life-threatening immune response that causes tongue and throat swelling, constricted blood vessels, hives, and hypotension (low blood pressure), according to the Mayo Clinic. Allergies to bees, medicine, nuts, and seafood are all common triggers for this kind of response.

“It’s rare but physical activity, usually vigorous, can be the trigger of anaphylaxis,” says Dr. Gupta. “Usually, there are other subtle triggers that work in conjunction with physical activity.” Symptoms can range from a red face, wheezing, stomach pain, diarrhea, or more severe symptoms like angioedema (swelling), laryngeal edema (throat closing), hypotension (low blood pressure), and, ultimately, cardiovascular collapse (fatal malfunctioning of heart and blood vessels), Dr. Gupta says. These more intense and dangerous symptoms are sure signs that you should stop what you’re doing and seek treatment.

How common is EIA

So, no, this is unlikely to fly as a reason for sitting out of running the mile in gym class—unless you have a doctor’s note. EIA is rare and even rarer without the presence of an existing allergy trigger, Dr. Gupta says. “Currently, it is believed that exercise-triggered anaphylaxis is linked to the foods that someone eats within 1 to 3 hours of exercise,” says Bradley Katz, MD, PhD, professor of neurology, and physician at the University of Utah Hospital.

Foods like shellfish or peanuts may be a trigger, and when someone exercises, blood flow increases and the body burns food more quickly, which can trigger an allergic reaction, Dr. Katz explains.

How do people manage exercise-induced allergic reactions

There’s good news: People with this allergy don’t have to omit all physical activity from their lives. “I was first diagnosed with exercise-induced anaphylaxis when I was 15. What my family and allergist thought was severe allergies to cats was actually exercise-induced anaphylaxis,” says Cynthia Bailey, MD, dermatologist and someone who experiences EIA. “I’ve had it many times since, and mine appears to be triggered by eating walnuts and then exercising. If I eat the walnuts without exercising, I get hives in my mouth, but if I exercise, I get full angioedema of my face and hands, wheezing, and—in some episodes—laryngeal spasm that requires treatment,” Dr. Bailey says.

Still, if you suspect you have EIA (or allergies in general), you don’t have to give up your favorite workouts. Dr. Katz recommends that focus keep a log of foods that they are sensitive to and make sure to avoid them—especially before exercise.

Treatments for EIA include antihistamines in mild cases or epinephrine injections (known as EpiPens). EpiPens, according to the Mayo Clinic, release the hormone epinephrine, which causes blood vessels to constrict rapidly and prevents the influx of throat-closing and skin-swelling antibodies. In most cases, people carry EpiPens in the event of emergencies, Dr. Gupta says. These tools buy the affected person time to get to a hospital for treatment, but they are not meant to solve the allergic reaction responses on their own.

Additionally, making sure you ease into a sport or maintain a medium intensity level can protect you from an attack, Dr. Katz says. And, if you have an allergic reaction, stop what you’re doing and seek treatment for any symptoms. But remember, exercise is not always dangerous. He adds that it depends on the allergy severity and other triggers you have.

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