Cholinergic urticaria with anaphylaxis: hazardous duty of a deployed US marine.

Cholinergic urticaria (CU) is triggered by a rise in body temperature and can be complicated by bronchial hyperresponsiveness and anaphylaxis. It primarily affects young adults who actively engage in strenuous exercise, such as servicemen and servicewomen. If the patient reports a history of wheezing or difficulty breathing with urticaria, a water challenge test in a warm bath can be performed to confirm the presence of anaphylaxis. The test should be conducted in an environment in which the patient's airway can be secured and epinephrine can be administered if necessary. Nonsedating antihistamines commonly are used to treat CU, but few other treatments have been thoroughly evaluated for cases that are refractory to antihistamines. We present the case of a 27-year-old US Marine with CU and anaphylaxis confirmed by a water challenge test in a warm bath.