Keratolytic — Warts / Psoriasis / Hyperkeratosis Pregnancy: Low-concentration topical use (2–6%) generally considered safe; avoid high concentrations over large areas — systemic salicylate absorption

Salicylic Acid

Brand names: Duofilm (with lactic acid), Occlusal, Verrugon, Capasal (shampoo with coal tar)

Adult dose

Dose: 2–40% (concentration depends on indication): warts 12–26%; psoriasis/hyperkeratosis 2–6%; scalp psoriasis — shampoo formulations

Route: Topical

Frequency: Once daily (warts) or as directed; scalp shampoo 2–3 times weekly

Max: Highest concentration (40%) for recalcitrant warts under occlusion; limit to small areas

Keratolytic agent breaking down keratin — used for warts/verrucae, psoriasis (scalp and body), hyperkeratosis, ichthyosis, acne, and seborrhoeic dermatitis. Higher concentrations (25–40%) for warts; lower concentrations (2–6%) for psoriasis and acne.

Paediatric dose

Dose: Apply to affected area only topical/kg

Route: Topical

Frequency: Once daily

Max: Avoid concentrations >10% in children; avoid large surface areas

BNFc: warts — 12–26% preparations for children; Duofilm licensed from 2 years. Avoid in children <2 years.

Dose adjustments

Renal

No dose adjustment for topical use (avoid high concentrations over large areas in renal impairment — salicylate absorption risk)

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Patient weight (kg)

BNFc: warts — 12–26% preparations for children; Duofilm licensed from 2 years. Avoid in children <2 years.

Clinical pearls

Wart treatment: file wart weekly (emery board/pumice stone), soak in warm water, apply salicylic acid preparation, cover with plaster — persistence is key; most warts resolve spontaneously in 2 years without treatment
Cryotherapy vs salicylic acid: RCT evidence shows salicylic acid and cryotherapy have similar efficacy for warts — NICE recommends either; salicylic acid first-line for plantar warts
Psoriasis: salicylic acid removes scale before topical steroids/calcipotriol — improves penetration; useful in scalp psoriasis shampoo formulations
Salicylate toxicity: tinnitus, dizziness, hyperventilation — avoid high concentrations over large areas, especially in children; never use 40% preparations on large surface areas
Combination products: Duofilm (salicylic acid + lactic acid) — lactic acid softens keratin further, enhancing salicylic acid penetration

Contraindications

Salicylate hypersensitivity (aspirin allergy — cross-reactivity)
Broken or inflamed skin
Facial warts (risk of scarring with high concentrations)
Large surface area application (salicylate toxicity risk)

Side effects

Local skin irritation (burning, stinging)
Skin ulceration (excess concentration)
Salicylate toxicity (large area/high concentration — tinnitus, dizziness)
Skin maceration under occlusion

Interactions

Other keratolytics — additive irritation

Monitoring

Treatment response at 4–6 weeks
Signs of salicylate toxicity (large area use)

Reference: BNFc; BNF 90; BNFc; NICE CKS Warts and Verrucae; Gibbs et al. Cochrane (2012) Treatments for cutaneous warts. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways