Cholinergic urticaria in a jogger: ruling out exercise-induced anaphylaxis.

Cholinergic urticaria is a systemic response to a rise in core temperature that can be brought on by exercise, as in this case of a 24-year-old jogger. Many cases, however, are mild. The exact pathophysiology for the release of histamines is unknown, but the resulting rash can be distressing for patients. The challenge for physicians is to differentiate exercise-induced urticaria from exercise-induced anaphylaxis, a potentially life-threatening condition. Effective management includes patient education, antihistamine use, if needed, and avoidance of precipitating triggers, such as strenuous exercise or hot showers.