Heat Rash Information

Heat rash occurs when sweat is trapped under the skin due to blocked sweat ducts and can range from intense itching and stinging of the skin to a severe condition that calls for immediate medical attention. Although most common in babies, heat rash can also affect children and adults, especially in hot, humid weather. However, you can treat and prevent heat rash simply by keeping skin cool and dry.

Symptoms

• Heat rash usually develops on the back, stomach, neck, upper chest, groin or armpits in adults and on the head, neck, shoulders or chest in babies and small children. Symptoms can vary depending on the severity of the rash. A mild form of heat rash, which is most common in babies and usually clears up on its own, affects only the top layer of skin and causes tiny, clear blisters or bumps with little to no pain or itching. A more irritating form of heat rash, more common in adults, affects the deeper layer of the outer layer of skin and causes red bumps surrounded by reddened skin along with itching or a prickly, stinging sensation. The most severe form of heat rash affects the deepest layer of skin, causing firm, flesh-colored lesions and a lack of perspiration, which may lead to heat exhaustion.

Causes

• Heat rash occurs when sweat ducts become clogged and perspiration is trapped under the skin. Factors that block sweat ducts include hot, humid weather in tropical climates; intense physical activity that causes extensive sweating; confinement to a hospital bed for long periods of time; clothing that prevents sweat from evaporating normally; heavy cream and ointments that block sweat ducts; and general overheating of the body. Babies are especially prone to heat rash in hot weather or when dressed too warmly due to undeveloped sweat ducts. Newborns with a high fever or in incubators can also develop heat rash.

Complications

• Areas of the skin affected by heat rash may become infected, causing inflamed, itchy pustules when scratched or irritated by clothing. People affected by the most severe form of heat rash are at risk of heat exhaustion, a life-threatening condition that causes low blood pressure, fever, dizziness, nausea, headaches and a rapid pulse and can lead to heatstroke.

Treatment

• With proper treatment, heat rash usually clears up in seven to 10 days. To treat mild heat rash, reduce sweating and cool skin by staying indoors and using air-conditioning or fans to circulate air and by limiting physical activity. If you must go outside in hot weather, wear lightweight, loose clothing that allows your skin to breathe. More severe forms of heat rash require topical treatments, including calamine lotion or hydrocortisone cream to relieve itching, and anhydrous lanolin to prevent sweat duct blockage and the development of new lesions. Extreme cases of heat rash may require topical steroids.

Prevention

• To prevent heat rash, keep your skin cool and dry; wear loose, lightweight cotton fabrics in the summer and avoid overdressing in winter, especially when dressing babies and children. When the weather is hot and humid, spend most of your time indoors with air-conditioning or fans. You should also keep your sleeping area cool, bathe with cool water and use soap without fragrances or dyes and avoid excessive use of cream and ointments, which can clog pores and sweat ducts.