If you have hives while exercising, your body may be having an allergic reaction to physical exertion or sweat. In most cases, hives are just uncomfortable nuisances, but in severe cases they can be one of many symptoms that result in a life-threatening allergic reaction. If you’re having difficulties breathing, seek emergency medical attention.
Exercise-induced urticaria causes weals that vary in size and may resemble red spots, blotches or blisters. The hives can occur anywhere on your body and like most hives, are very itchy. In mild cases of exercise-induced urticaria, bumps are all that occur, but severe cases include labored breathing, swelling of the face and tongue, headache and abdominal cramping. The hives will usually disappear within a few minutes of stopping exercise. Cholinergic urticaria is similar in appearance to exercise-induced urticaria. The skin may have a warming sensation where the hives are present and as the weals grow in size, they can join to form a large area of swelling. Cholinergic urticaria usually appears on the upper trunk and arms. A heat rash can be mistaken for hives. Heat rash has a prickly sensation and the area of the rash will have little to no sweat.
Exercise-induced urticaria is directly caused by your body having an allergic response to exercise. Cholinergic urticaria is caused by sweating that results from a rise in your body temperature. Exercising in hot weather makes you more susceptible to cholinergic urticaria. You may also notice these hives while taking a hot bath or when you have a fever. Miliaria rubra is the form of heat rash you’re likely to experience while exercising. Miliaria rubra is caused by your sweat ducts becoming clogged. Under normal circumstances, sweat evaporates, but heat rash develops from sweat being trapped under the skin. Heat rash can occur during intense exercise and if you’re wearing clothes that don’t allow sweat to evaporate.
Stop exercising if you notice hives. If the hives do not disappear within 10 minutes or are accompanied by other symptoms, contact your doctor. If you have exercise-induced urticaria, exercise with someone aware of your condition. Antihistamines can be used to treat exercise-induced urticaria and cholinergic urticaria. If you have cholinergic urticaria, rapid cooling in a cold shower can help relieve symptoms. Calamine lotion can relieve itching from heat rash and anhydrous lanolin can prevent your ducts from becoming blocked.
If you have an allergic reaction to exercise or sweating, always take your medications as prescribed to avoid hives. You may need to avoid vigorous-intensity exercises or follow an approved exercise routine designed by a medical professional. For cholinergic urticaria and heat rash, preventing sweating is the best way to prevent hives. Exercise in an air-conditioned areas and wear lightweight clothing. Avoid ointments and lotions that can block the pores and make you prone to heat rash.