Exercise-induced anaphylaxis and urticaria are allergic conditions that flare up when a person exercises. Both are triggered by an overreaction of the immune system. However, anaphylaxis (a generalized allergic reaction involving two or more body systems) is a much more dangerous condition than urticaria (red, swollen patches of skin) and may require emergency medical treatment.

Anaphylaxis can include urticaria along with other symptoms (such as wheezing), and may progress to anaphylactic shock, a potentially life-threatening condition that requires immediate treatment.

Younger people are at higher risk for experiencing exercise-induced anaphylaxis and urticaria. In addition, women and those with a family history of atopy (genetic tendency toward allergies) are more likely to experience exercise-induced anaphylaxis.

Antihistamines can be prescribed to both treat and prevent cases of exercise-induced urticaria. However, there is no similar preventative medication for exercise-induced anaphylaxis, and a flare up of this rare condition may require an emergency injection of the drug epinephrine to save the patient’s life.