A hair follicle is a small cavity of the skin in which a hair develops. When one or more of these becomes inflamed or infected, it is called folliculitis. Hot tub folliculitis is an infection of the hair follicles that occurs after being in a hot tub.
Bacteria called Pseudomonas aeruginosa can grow in hot tub water that is not adequately treated with chemicals. When a person soaks in the water, the bacteria can enter the hair follicle. This causes an infection.
Hot tub folliculitis is caused by exposure to contaminated water in a hot tub or spa. People with open cuts or sores, people with diabetes, or those have a history of other skin conditions are at increased risk for infection.