Regular swimmers, whether in indoor pools or open water, commonly present at the pharmacy counter with two distinct skin complaints: chlorine-induced contact dermatitis and cercarial dermatitis, colloquially known as swimmer's itch. Both cause itching and redness, but they have different causes and require different approaches.
Chlorine dermatitis: the pool swimmer's problem
Chlorine is the most widely used disinfectant in UK swimming pools. While effective at killing pathogens, it strips the skin's natural lipid barrier, particularly with frequent or prolonged exposure.
Symptoms typically include dry, tight-feeling skin after swimming, redness and itching — especially in skin creases, the axillae and behind the knees — and occasionally a diffuse erythematous rash on the trunk and limbs. In more severe cases, the skin may crack or develop an eczematous appearance.
What pharmacists can recommend
Barrier protection before swimming. Applying an emollient such as a paraffin-free barrier cream before entering the pool can reduce chlorine contact. Dimethicone-based products are commonly used, though evidence for their effectiveness in this context is limited.
Post-swim care. Showering immediately after swimming and applying an emollient within minutes of drying helps restore the skin barrier. Products containing urea (5–10%) or glycerol are suitable choices.
For active irritation. A mild topical corticosteroid such as hydrocortisone 1% cream, applied thinly to affected areas twice daily for up to seven days, is appropriate for adults and children over 10 years. Emollient-based wash products can replace soap in the shower. An antihistamine such as cetirizine or loratadine may help manage itching.
When to refer. If symptoms persist beyond two weeks despite OTC treatment, or if the skin becomes cracked, weeping or shows signs of secondary infection, a GP referral is appropriate.
Swimmer's itch (cercarial dermatitis): the open-water concern
Cercarial dermatitis is caused by the larvae (cercariae) of certain flatworm parasites that infest freshwater snails. When a swimmer enters infested water — typically still or slow-moving lakes and ponds — the larvae can penetrate the skin. They cannot survive in humans and die within the dermis, triggering an immune response.
According to NHS guidance, the condition is self-limiting but can be intensely uncomfortable. Symptoms appear within hours of exposure: an initial tingling or prickling sensation, followed by small red papules that develop into intensely itchy raised spots. The rash typically affects exposed skin not covered by swimwear.
Pharmacy management
Symptomatic relief. Oral antihistamines (cetirizine 10mg or loratadine 10mg daily for adults) help control itching. Calamine lotion or a cooling menthol-in-aqueous cream preparation can provide topical relief.
Anti-inflammatory treatment. Hydrocortisone 1% cream applied to affected areas can reduce inflammation. For more widespread rashes, an emollient containing colloidal oatmeal may soothe irritation.
Infection prevention. Advise against scratching, as secondary bacterial infection is the main complication. If spots become pustular, painful or develop spreading redness, refer to a GP for possible antibiotic treatment.
Prevention advice
For open-water swimmers, practical prevention measures include towelling off vigorously immediately after leaving the water (this can dislodge cercariae before they penetrate the skin), avoiding shallow, weedy areas where snail populations concentrate, and applying a water-resistant barrier cream before swimming.
Distinguishing the two conditions
| Feature | Chlorine dermatitis | Swimmer's itch |
|---|---|---|
| Water type | Chlorinated pools | Fresh open water (lakes, ponds) |
| Onset | During or shortly after swimming | Hours after swimming |
| Appearance | Diffuse dryness, redness | Discrete papules, raised spots |
| Distribution | Generalised, worse in creases | Exposed skin only |
| Duration | Days (with emollient care) | 1–3 weeks (self-limiting) |
| Recurrence | With continued pool use | Sensitisation makes repeat episodes worse |
A note on pool rashes in children
Children are particularly susceptible to both conditions. Their thinner skin barrier makes them more vulnerable to chlorine irritation, and they tend to spend longer in the water than adults. Parents seeking advice should be reassured that both conditions are common and manageable, but should return if symptoms worsen or the child develops a fever, which may indicate a different diagnosis.
Finding pharmacy support
Pharmacists across the UK can advise on skin conditions and supply appropriate OTC treatments without a GP appointment. Use PharmSee's pharmacy finder to locate a pharmacy near you, or check local pharmacy opening hours including evenings and weekends.
Sources: NHS, NICE CKS Contact Dermatitis guidance, BNF.