Exercise-Induced Allergic Reactions
Exercise-induced allergic reactions occur during or after exercise.
Exercise often triggers an asthma attack in people who have asthma, but some people have asthma only when they exercise. Exercise may trigger or worsen asthma because breathing fast cools and dries the airways, and as the airways warm again, they narrow. Exercise-induced asthma is more likely to occur when the air is cold and dry. The chest feels tight. The person may wheeze and have difficulty breathing.
Rarely, vigorous exercise triggers an anaphylactic reaction. In some people, this reaction occurs only if they eat a specific food before exercising. Breathing becomes difficult or blood pressure falls, leading to dizziness and collapse. An anaphylactic reaction can be life threatening.
Typically, symptoms triggered by exercise--asthma or an anaphylactic reaction--occur after 5 to 10 minutes of vigorous exercise. Often, symptoms begin after exercise has stopped.
The diagnosis is based on the symptoms and their relationship to exercise. An exercise challenge test can also help doctors make the diagnosis. For this test, measurements of lung function are made before and after exercise on a treadmill or stationary bicycle (see Section 4, Chapter 44).
Treatment
For people with exercise-induced asthma, the goal of treatment is to be able to exercise without symptoms. Becoming more physically fit may make the development of symptoms during exercise less likely. Inhaling a beta-adrenergic drug (such as those used to treat asthma (see Section 4, Chapter 44)) about 15 minutes before starting to exercise often helps prevent reactions. Cromolyn, usually taken through an inhaler, may be helpful.
For people who have asthma, taking the drugs usually used to control asthma often prevents symptoms from developing during exercise. For some people with asthma, taking drugs to treat asthma and gradually increasing the intensity and duration of exercise enables them to tolerate exercise.
People who have had an exercise-induced anaphylactic reaction should avoid the form of exercise that triggered the attack. If eating a specific food before exercise triggers symptoms, they should not eat the food before exercise. A self-injecting syringe of epinephrine should always be carried for prompt emergency treatment. Exercising with other people is recommended.
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