Your skin is the barrier between your body and the outside world. It is subject to attack by bacteria, irritants and parasites as well as fungal infections and viruses. Internal conditions, particularly autoimmune diseases, can affect the skin as well. According to the "Cecil Textbook of Medicine," there are many hundreds of reasons for the skin to develop problems. Skin conditions after swimming, however, are most commonly associated with exposure to marine life or infection by bacteria specific to water.
"Swimmer's itch" is caused by the tiny larvae of a snail parasite. This rash develops within an hour of exposure and itching may start before the rash appears. Fortunately, the condition is usually harmless and resolves without any special treatment in 3 days to 2 weeks. The parasite cannot grow in humans, but larvae float in the water and attach to human skin by means of small suckers. The parasite attempts to burrow in the skin but quickly dies, triggering an allergic reaction. This rash appears on areas of the body that came in contact with the water; areas covered by clothing or swimsuits are less affected.The most severe form is seen after exposure to the freshwater lakes of the northern U.S.
Swimming Pool Granuloma
This rash occurs in damaged skin that has been exposed to contaminated water. It is caused by an unusual bacteria called mycobacterium marinum, and can be readily treated with the correct antibiotic. It will not respond to the usual antibiotics prescribed for skin infections, and often persists until a small piece of skin is sent to the laboratory for culture. This testing can correctly identify the bacteria and allow your doctor to prescribe the correct antibiotic.
Sea Bather's Eruption
"Sea bather's eruption" or "sea bather's dermatitis" is a rash that can develop after swimming in the ocean along the Atlantic coast of the U.S. or the Caribbean. It is a reaction to stinging jellyfish larvae, or other marine larvae. It can be intensely itchy and occurs shortly after getting out of the water. The larvae sting in self-defense when they are trapped under bathing suits, swimming caps or hair. The rash will resolve itself within 14 days. Typically, this rash is the most severe in areas covered by clothing.
Hot Tub Folliculitis
"Hot tub folliculitis" is a rash caused by the bacteria pseudomonas aeruginosa. This bacteria can contaminate hot tubs, swimming pools and whirlpools that are not properly chlorinated and are maintained at warm temperatures. The rash begins 6 hours to 5 days after contact and will typically affect all who were exposed to the water. The rash does not affect the neck and head. Most of the time the rash resolves in 7-10 days without specific treatment, although "Harrison's Principles of Internal Medicine" warns that severe infections have been reported.