(NEW YORK) -- An allergy to exercise might sound like a couch potato's dream, but for Kasia Beaver, a mom of four who lives in the U.K., it's a nightmare.
Whenever her heart beats too fast and she sweats, it sparks a potentially fatal allergic reaction. Her eyes swell shut, she breaks out in hives and her throat closes up.
"It's terrifying, especially if I'm alone with the children," she said.
The 33-year-old is just one of a handful of people who suffer from a life-threatening allergic reaction to exercise known as exercise-induced angioedema -- or EIA. The condition and a less severe form of exercise allergy called exercise-induced urticaria are so exceedingly rare, there are no estimates for the number of sufferers.
But Dr. Dennis Cardone, a sports medicine specialist at the NYU Langone Medical Center in New York, said exercise allergy is a real condition.
"Typically we see it in combination with another type of allergy, usually to food or hot weather," Cardone said.
As Cardone explained it, people with the condition may be able to eat peanuts or shellfish with no reaction and they may also be able to exercise with no problem. But if they eat peanuts or shellfish before they exercise, it triggers an attack.
EIA doesn't appear to have any association with exercise-induced asthma or any other type of breathing or exercise-related disorders.
Cardone said the chemistry is the same as for most other allergies. The immune system mistakes a harmless substance for a dangerous intruder and responds by producing antibodies. These trigger special "mast cells" to produce chemical "histamines" that react with the rest of the body to produce the physical symptoms of an allergy.
An allergy to exercise generally isn't considered life-threatening. However, in Beaver's case it is. Doctors have told her that running for a bus or chasing after her children could kill her.
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