Medical Author: Melissa Stoppler, M.D. Medical Editor: William C. Shiel, Jr, MD, FACP, FACR Hot tub rash is an infection of the skin (dermatitis) or of the hair follicles in the skin (folliculitis) acquired from contact with contaminated water. The infection occurs most commonly after swimming in hot tubs or spas, but contaminated swimming pools or lakes may also spread the infection.

Most cases of hot tub rash are caused by the bacterium Pseudomonas aeruginosa, an organism abundant in nature and found in soil, water, and on plants. Hot tub rash usually begins with itchy skin or itchy bumps on the skin, which progress to form tender red nodules that may contain pus. Pus-containing sores are also commonly present around hair follicles. The rash is often worse under the areas of skin covered by a swimsuit, since the swimsuit can keep the contaminated water in contact with the skin for a longer period of time. Hot tub rash appears within two days after contact with contaminated water.

Hot tub rash generally resolves on its own within a few days, and medical treatment is rarely necessary. Complications of hot tub rash are rare and include abscess formation. In severe cases or when a skin abscess develops, you doctor may prescribe an antibiotic.

Frequent testing of water in pools and hot tubs and adequate control of disinfectant levels and pH are critical steps in preventing hot tub rash. Since hot tubs have warmer water than pools, disinfectants such as chlorine break down and lose their effectiveness faster in hot tubs than in pools. Thorough cleaning and disinfecting of a pool or hot tub where the infection has been acquired is also essential to prevent recurrence of the rash

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