Apart from the usual causes of anaphylactic reaction—medications, insect stings, food, and dust, a distinct form of anaphylaxis occurs as a result of strenuous activities like exercise. In susceptible persons, the word “exercise” encompasses jogging, sports, or even walking.

Precipitating Event

Although the exact mechanism of the allergic reaction is still unknown, the condition is closely related to the ingestion of offending agents like food and medication. In rare cases, EIA is experienced even without the abovementioned agents. Laboratory findings suggest that mast cells burst open releasing chemicals, like leukotriene and histamine which causes the allergic reaction.

Common allergens like nuts, shellfish, poultry, cereal grains, dairy, and alcohol are associated with EIA. Wheat is also thought to cause a wheat-dependent exercise-induced anaphylaxis. The combination of food and exercise causes symptoms like generalized warmth, itching of the entire body, and hives that begin within minutes upon starting the activity. The condition may rapidly progress to shortness of breath, wheezing, dizziness that signals the narrowing of the airways; a sudden drop in blood pressure may also occur due to the massive dilation of the blood vessels.

What your Doctor can do for you

There are few documented cases of exercise-induced anaphylaxis. In fact, only one death has been attributed to this condition. Diagnosis is based heavily on history of symptoms that occur only during exercise. A pre-existing allergy or asthma is also assessed. The suspected person may also need to perform an exercise challenge test under the supervision of a physician with equipment immediately available in cases of a fatal reaction. Skin tests are also necessary to determine the food that may have triggered the anaphylaxis.

Any anaphylactic reaction is a medical emergency that requires immediate intervention. Establishing a patent airway and appropriate ventilation is essential by administering epinephrine to provide rapid relief. The route of administration may vary depending on the severity of the symptoms. Subcutaneous route is used for mild disorders while intramuscular route is preferred when the reaction is severe and rapidly progressing and there is an impending cardiovascular collapse. Intravenous route is used in rare instances if there is complete loss of consciousness and severe cardiovascular collapse. Endotracheal intubation may be required to avoid loss of the airway. Resuscitative measures are used especially in patients experiencing laryngeal and pulmonary edema.

Additional medications include antihistamines and bronchodilators. Mast cell stabilizers may be prescribed to prevent future attacks.

What you can do

People with suspected EIA should avoid exercising without a companion, and must always wear a Medic Alert bracelet. The food associated with the reaction must be avoided prior to exercise. And if exercise cannot be avoided, always bring an emergency kit containing the prescribed amount of epinephrine (EpiPen).