Topical Treatment for Verruca (Warts)
Salicylic acid 15-40% topical paints or ointments is the recommended first-line topical treatment for verrucae, applied after paring or debridement of the wart. 1, 2, 3
Primary Topical Treatment Approach
Salicylic Acid (First-Line)
- Salicylic acid works by promoting exfoliation and acts as an irritant at higher concentrations, potentially stimulating host immunity against warts 2
- Meta-analysis demonstrates warts treated with salicylic acid are 16 times more likely to clear than placebo, with a mean cure rate of 49% versus 23% for placebo 2
- FDA-approved salicylic acid 6% is indicated as a topical aid for removal of excessive keratin in verrucae 3
Application Technique (Critical for Success)
- Lesions must be abraded, pared down, and/or soaked prior to salicylic acid application 2
- Apply thoroughly to affected area and cover at night after washing 3
- Hydrate skin for at least 5 minutes before application 3
- Wash off in morning; if excessive drying occurs, apply bland cream 3
- Occlusion has shown benefit when using salicylic acid gel with lactic acid 2
Concentration by Wart Location
- Plantar warts (verrucae): 15-40% topical paints or ointments 1, 2
- Hand warts: 15-40% topical paints or ointments 1, 2
- Plane warts (flat warts): Lower concentrations of 2-10% cream/ointment or cautious use of 12-17% paint without occlusion 1
- Facial warts: Salicylic acid paints are contraindicated due to risk of irritant burning; only 2% creams may be considered 2
Alternative Topical Agents
Trichloroacetic Acid (TCA) or Bichloroacetic Acid (BCA)
- Apply 80-90% concentration sparingly only to warts and allow to dry until white "frosting" develops 1
- If excess applied, powder with talc, sodium bicarbonate, or liquid soap to remove unreacted acid 1
- Can be repeated weekly if necessary 1
- These are caustic agents that destroy warts by chemical coagulation of proteins 1
Podophyllotoxin
- Podofilox 0.5% solution or gel is patient-applied, relatively inexpensive, and safe 1
- Most patients experience mild to moderate pain or local irritation 1
- Listed as alternative treatment for plantar warts in British guidelines 1
Imiquimod
- Topically active immune enhancer that stimulates interferon and cytokine production 1
- Local inflammatory reactions are common but usually mild to moderate 1
- Listed as alternative for plane warts and facial warts 1
Other Topical Options (Lower Evidence)
- Formaldehyde 3-10% solution: Reported 80% cure rate in open study of 646 children with plantar warts, but allergenic 1
- Glutaraldehyde 10% paint: Equivalent to salicylic acid for plantar warts with 72% cure rate, but risk of deep necrosis with repeated application 1
- 5-Fluorouracil (5-FU): 0.5% in combination with 10% salicylic acid appears much more effective than salicylic acid alone (63% vs 11% clearance) 1
- Dithranol 2% cream: Small RCT showed 56% cure rate versus 26% for salicylic acid combination product 1
Treatment Duration and Monitoring
- If no response after 3 months of consistent treatment, consider alternative or combination therapies 2
- Once clearing is apparent, occasional use of salicylic acid maintains remission 3
- Excessive repeated application does not increase benefit but could result in increased local intolerance and systemic salicylism 3
Critical Safety Considerations
- All but very low-strength salicylic acid can cause chemical burns 2
- Contraindicated in areas of poor healing such as neuropathic feet 2
- Contraindicated on the face due to risk of irritant burning 2
- Paring should avoid damaging surrounding skin due to risk of spreading infection 1
- Compliance is often poor due to irritation of surrounding skin 2
- Podophyllin is contraindicated in pregnancy due to dangerous systemic effects 1
Combination Therapy Consideration
- Salicylic acid combined with cryotherapy using more aggressive regimens is probably more effective than standard regimens, though with worse side-effects 1
- One study of combined cryotherapy with 70% salicylic acid showed 89.2% eradication rate 4
- However, a large RCT found no difference between cryotherapy and 50% salicylic acid alone at 12 weeks (14.3% vs 13.6% clearance) 5