Pseudomonas folliculitis (hot-tub folliculitis)
Hot-tub folliculitis; Pseudomonas aeruginosa folliculitis; whirlpool dermatitis
Pseudomonas folliculitis (commonly known as hot-tub folliculitis) is a self-limiting pruritic papulopustular eruption caused by Pseudomonas aeruginosa following exposure to contaminated pools, hot tubs, jacuzzis or shaving with contaminated implements. It typically appears 8–48 hours after exposure as pruritic erythematous papules and pustules in a swimwear distribution, often sparing the head and neck (except diving). In skin-oncology it is the principal mimic of EGFR-inhibitor papulopustular eruption and BRAFi cutaneous reactions — patients on these therapies who use hot tubs should be counselled, and clinical distinction matters because pseudomonas folliculitis self-resolves rather than warranting drug interruption.
Clinical features
- Pruritic erythematous follicular papules and pustules, 2–10 mm.
- Distribution — swimwear / immersion area, sparing the head and neck (except after diving).
- Onset 8–48 hours after pool / hot tub exposure.
- Constitutional symptoms — sometimes mild fever, malaise, conjunctivitis, headache.
- Otitis externa ("swimmer's ear") may coexist.
- Self-limiting — most cases resolve over 7–14 days without treatment.
Skin-oncology context — distinguish from EGFRI / BRAFi reactions
- EGFRI papulopustular eruption — sterile, in a seborrhoeic distribution (face, scalp, upper chest); not swimwear distribution; onset 1–3 weeks after starting therapy.
- BRAFi cutaneous reactions — include acneiform but also verrucous papillomas, secondary cSCC; predominantly facial.
- Pseudomonas folliculitis — clear hot-tub exposure history; swimwear distribution; rapid onset; self-resolving.
- Counsel patients on ICI / EGFRI / BRAFi about hot-tub use — both as a confounder and because immunosuppressed patients may have more severe pseudomonas disease.
- Bacterial swab to confirm where unclear; treat MRSA where suspected.
Management
- Reassurance — self-resolving within 7–14 days.
- Topical 2.5% acetic acid or dilute white vinegar compresses — kills Pseudomonas.
- Topical or oral ciprofloxacin in severe / extensive / immunosuppressed disease.
- Avoid contaminated source — disinfect / abandon hot tub; check pool chlorination.
- Trim / shave with clean implements only.
- Otitis externa — topical ciprofloxacin drops.
References
- Maniatis AN et al. Pseudomonas aeruginosa folliculitis due to non-O:11 serogroups — acquisition through use of a contaminated home whirlpool spa. Clin Infect Dis; 1995.
- CDC — Hot tub folliculitis fact sheet.
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