Can You Really Be Allergic to Exercise? Actually, Yes—Here's What Experts Say

It's hard to argue that exercise is bad for your health in the face of an enormous body of evidence that tells us otherwise. But for some people, such as TikTok user Kira (@snflwrxtrnsl), exercise actually is harmful—because her doctors believe it caused her to have a serious allergic reaction.

In a recent video posted to TikTok, Kira mouths the lyrics to Lady Gaga's "Bad Romance" against a backdrop montage of images. The first, showing her outdoors in running gear, was captioned, "me going on a normal run for gym class." The next said, "me getting really tired way too fast but thinking nothing of it."

Then it gets more serious. "My whole body starting to itch like crazy and my face blowing up," she wrote. She goes on to reveal that she had to call her mom to pick her up because she was feeling faint and had trouble breathing. But her ordeal wasn't over. Back home, she and her mom had to call 911 because she was "becoming blind." The next image was of Kira in the back of an ambulance, with the caption, "me rushed to the hospital given 3 epipens on the way." She finished the clip by revealing that her doctor told her she was "probably allergic to exercise."

In the comments, Kira revealed that she "literally got a doctors note so I can't do gym class anymore."

How Can Someone Be Allergic To Exercise?

Allergic reactions typically occur due to a number of things, like pollen or dust mites, and range from minor to major, MedlinePlus says. On the major side of things, anaphylaxis (a potentially life-threatening allergic reaction) could occur in situations where a person is exposed to certain foods and medications or stung by specific insects, according to MedlinePlus. But it also notes that exercise can be a culprit too.

While we don't know for sure if Kira was indeed allergic to exercise, it's possible...kind of. A rare condition called exercise-induced anaphylaxis (EIA) occurs when someone reacts to an allergen in conjunction with exercise. It was first described in 1979 in a case report published in the Journal of Allergy and Clinical Immunology, and is thought to affect around 50 in every 100,000 people.

"Exercise-induced anaphylaxis is a rare entity that occurs when people go into a life-threatening severe allergic reaction that can include wheezing, rash, breathing issues, and shock," Purvi Parikh, MD, an allergist and immunologist at NYU Langone Health, told Health.

There's also a subtype of EIA known as food-dependent exercise-induced anaphylaxis (FDEIA), where both trigger foods (e.g., wheat) and physical activity are required to induce anaphylaxis. "Prevalence of FDEIA is not well known, but it has been reported to be about a third or half of all EIA cases. Symptoms and presentations are similar to those of EIA, and people with this syndrome don't react to the food or the exercise alone," Brian Jin Choi, DO, a sports medicine physician with Hoag Orthopedic Institute in Orange County, California, told Health.

What Are the Symptoms?

Common symptoms include the typical symptoms of an allergic reaction, including but not limited to itchy skin, hives, angioedema (swelling underneath the skin), flushing, shortness of breath, gastrointestinal symptoms (e.g. nausea and diarrhea), headache, and loss of consciousness, Dr. Jin Choi said. He also added that death from this condition is very rare, but it should still be considered as potentially life-threatening.

What Causes EIA/FDEIA?

It's not clear. "The exact mechanism between exercise and anaphylaxis is poorly understood, but there is a link between foods that are eaten within three hours of heavy exercise that trigger this reaction," Dr. Parikh said. Any food can be a trigger, but common culprits are shellfish, wheat, seafood, nuts, cereal, dairy, and celery. It may also be exacerbated by alcohol intake, or ingestion of aspirin or non-steroidal anti-inflammatory drugs (NSAIDs).

EIA/FDEIA is usually triggered by moderate-intensity exercises, most commonly jogging, but can occur with any intensity level of exercise. "Episodes are not fully predictable, in other words the same intensity and type of exercise may or may not induce the symptoms every time," Dr. Jin Choi said. "Some external factors may play a role as well, such as humidity and warm or cold weather."

There are various theories about what's going on, such as increased blood flow in the body during exercise, which might displace sensitive immune cells. Another is that some proteins in the gut behave in a certain way during physical activity and interact with food or medication in a way that causes an allergic reaction.

Are There Any Risk Factors?

EIA/FDEIA can occur in any age group, but it appears to be most common in the teens and 20s, Dr. Jin Choi said. "There is no known racial predilection and no clear gender predilection, although two large studies have reported that females are twice as likely to experience it than males."

Does Fitness Level Have Anything To Do With It?

It's unlikely. "There appears to be no relationship between fitness level and the predilection to EIA or FDEIA," Dr. Jin Choi said. "It is usually sporadic, but some cases are reported to be hereditary."

How Is It Treated, and Is There a Cure?

It is necessary to get immediate medical care if anaphylaxis occurs, so you'll need to call 911 or another local emergency number as soon as possible, per MedlinePlus. Additionally, if anaphylaxis is not treated quickly, there could be complications. Those complications might be a blocked airway, cardiac arrest, respiratory arrest, or shock, MedlinePlus says.

While waiting for emergency care, you can administer first aid, including:

• Calming and reassuring the person affected
• Administering injectable emergency medicine (epinephrine) as soon as the reaction happens
• Attempting to prevent shock, which means having the individual lie flat with their feet raised 12 inches high and covering them with a coat or blanket (unless there is a suspected injury or discomfort)

After an EIA/FDEIA reaction, the management methods are similar to those used to treat regular anaphylaxis, Dr. Jin Choi said. These include intramuscular epinephrine, antihistamine, systemic steroid, fluid resuscitation, and supportive care.

There isn't a cure for EIA/FDEIA, but there are various preventive steps you can take. The most important step is to avoid foods or medication that can trigger symptoms close to the time of exercising. Dr. Jin Choi also recommends avoiding exercise in hot, cold, or humid weather. Dr. Parikh suggests taking an antihistamine (like Zyrtec) 30 minutes before exercising. "I prescribe all my patients with exercise-induced anaphylaxis an EpiPen to keep close by," she adds.

In other words, you don't have to stop exercising completely after experiencing EIA/FDEIA, unless directed to do so by a healthcare professional—but you do have to be careful and aware of any triggers in order to keep the reaction at bay.