Hot Tub Rash (Pseudomonas aeruginosa Dermatitis

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Hot Tub Rash (Pseudomonas aeruginosa Dermatitis)


Disease History, Characteristics, and Transmission

Scope and Distribution

Treatment and Prevention

Impacts and Issues



Hot tub rash is a form of skin irritation that results from an infection caused by the bacterium Pseudomonas aeruginosa. This bacterium is commonly found in environments such as water and soil.

Disease History, Characteristics, and Transmission

Hot tub rash is a skin infection that is known as dermatitis. The infected skin becomes itchy, and a red rash develops 48 hours to several weeks after contact with contaminated water. The depressions in the skin that surround hair follicles can also become contaminated, which can lead to the development of pus-filled blisters, a condition known as folliculitis. Less commonly, hot tub rash can lead to other and more serious infections in the eye, breast, lung, and urinary tract.

The term hot tub rash reflects the prevalence of the infection in hot tubs, where warm water can provide ideal conditions for the growth of P. aeruginosa, buthottub rash is not exclusive to hot tubs. The skin infection can also occur from swimming in a contaminated lake or pool, and P. aeruginosa skin infections have also been documented in waterslides and bathtubs, as well as following the use of diving suits that have not been properly washed between use, particularly when someone has a cut or scratch in the skin. Any opening on the skin surface increases the likelihood that P. aeruginosa can establish an infection. Skin that is covered by a bathing suit can develop a more severe infection, as the contaminated water is held in closer and has more prolonged contact with the skin.

Chemicals such as chlorine, which are added to keep the water free from microorganisms, lose their potency more quickly at the elevated water temperatures in hot tubs. Back-yard or commercial hot tubs are sometimes inadequately disinfected, which also creates opportunity for the growth of P. aeruginosa.

The construction of a hot tub can contribute to P. aeruginosa growth. Many hot tubs are made of wood. Even if the tub's inner surface looks smooth, the wood will contain many tiny cracks in which the bacteria can grow. When growing on surfaces, P. aeruginosa often produces a sugary coating called an exopolysaccharide. The resulting exopolysaccharide-enclosed population of bacteria (which is called a biofilm) can become very resistant to chlorine and other disinfectants. Bacteria can slough off from the biofilm into the water; if someone is in the hot tub there can be an opportunity for the skin infection to develop. Even plastic hot tubs can have surface-adhering P. aeruginosa biofilms.


BIOFILM: Biofilms are populations of microorganisms that form following the adhesion of bacteria, algae, yeast, or fungi to a surface. These surface growths can be found in natural settings such as on rocks in streams, and in infections such as can occur on catheters. Microorganisms can colonize living and inert natural and synthetic surfaces.


To ensure safe and healty use, The Centers for Disease Control and Prevention (CDC) recommends that spa users observe the following rules to protect against recreational water illnesses:

  • Refrain from entering a spa when you have diarrhea.
  • Avoid swallowing spa water or even getting it into your mouth.
  • Shower or bathe with soap before entering the spa.
  • Observe limits, if posted, on the maximum allowable number of bathers.
  • Exclude children less than 5 years of age from using spas.
  • If pregnant, consult a physician before spa use, particularly in the first trimester.

SOURCE: Centers for Disease Control and Prevention (CDC)

Scope and Distribution

As P. aeruginosa is widespread in the environment, hot tub rash is also common. In a hospital, the infection is more of a concern, especially for patients with malfunctioning immune systems. In these patients, P. aeruginosa often causes infection in the moist tissues of the lung.

There is no age, race, gender, or geographical influence on the occurrence of hot tub rash.

Treatment and Prevention

Hot tub rash tends to clear without treatment in several weeks. However, some people can benefit from the use of an antibiotic-containing ointment that is rubbed onto the affected areas of the skin. This treatment may be ineffective, however, as some strains of P. aeruginosa are resistant to a variety of antibiotics.

For people at higher risk of more serious infection (such as those with an inefficient immune system), treatment with the antibiotic ciprofloxacin can be useful.

Hot tub rash can be prevented by avoiding environments where P. aeruginosa-contaminated water might be found. Most commonly, this means avoiding the use of a domestic hot tub, or not using a crowded hot tub. If this is unrealistic, then regular disinfection of the tub water and cleaning of the inside surface of the tub should be considered essential maintenance.

Impacts and Issues

While hot tub rash is often an inconvenience rather than a health concern, the infection can be serious for someone whose immune system is less able to fight off infection. In such people P. aeruginosa becomes an opportunistic pathogen—an organism that does not normally cause disease but which is capable of causing disease under the appropriate circumstances.

In an public environments such as hospitals or spas, whirlpools and hot tubs need to be regularly maintained and the water tested for the presence of microorganisms. The Centers for Disease Control and Prevention (CDC) recommends maintaining the free-chlorine or bromine level of the hot tub or pool between 2–5 parts per million and maintaining the pH level of the water at 7.5–7.8. As well, the whirlpool or tub should be located in a wellventilated room, as the agitation of the hot water could create aerosolized bacteria. If the bacteria become aerosolized, they can be inhaled, which can result in a lung infection. The possibility of a lung infection is especially serious for persons who have cystic fibrosis, since P. aeruginosa can establish a persistent infection that can progressively damage the lung tissue.

See AlsoSwimmer's Ear and Swimmer's Itch (Cercarial Dermatitis).



Tortora, Gerard J., Berell R. Funke, and Christine L. Case. Microbiology: An Introduction. New York: Benjamin Cummings, 2006.

Brunelle, Lynn, and Barbara Ravage. Bacteria. Milwaukee: Gareth Stevens Publishing, 2003.

Web Sites

Centers for Disease Control and Prevention. “Hot Tub Rash.” <> (accessed March 1, 2007).

Brian Hoyle