Application of 40% Salicylic Acid
40% salicylic acid should be applied as a plaster directly to corns after paring down the hyperkeratotic tissue, ensuring treatment covers less than 20% of body surface area to prevent systemic salicylate toxicity. 1
Indication and Formulation
- 40% salicylic acid plasters are specifically recommended for corn treatment, demonstrating superior outcomes compared to standard scalpel debridement alone 1
- This concentration is significantly higher than the 20-30% used for acne peels or the 0.5-2% used in over-the-counter products, making it appropriate only for localized hyperkeratotic lesions like corns 2, 1
Pre-Application Preparation
- Before applying the plaster, pare down or abrade the hyperkeratotic corn tissue to enhance penetration of the salicylic acid 1
- Exercise caution to avoid abrading surrounding normal skin during paring, as this may spread infection or cause unnecessary irritation 1
Application Method
- Apply the 40% salicylic acid plaster directly to the corn after tissue preparation 1
- The plaster formulation allows for sustained contact with the lesion while minimizing exposure to surrounding healthy skin 1
Critical Safety Limits
- Never apply salicylic acid to more than 20% of total body surface area to avoid systemic salicylate toxicity 1, 3
- Avoid combining with oral salicylate medications (including aspirin) due to additive systemic effects that can lead to salicylism 1, 3
- Use extreme caution in patients with impaired hepatic or renal function, as systemic absorption can occur and lead to accumulation 1, 3
Monitoring and Adverse Effects
- Monitor for excessive irritation, erythema, or scaling at the application site 1
- Watch for signs of systemic salicylate toxicity including tinnitus, dizziness, headache, mental confusion, and hyperventilation 2, 4
- Although rare, salicylism or even death can occur from topically applied salicylic acid, particularly when applied to large surface areas 4
Special Populations to Avoid
- Do not use in children under 2 years due to increased systemic toxicity risk 3
- Exercise caution during pregnancy (limit area and duration of exposure) and use only for localized application during breastfeeding 3
- Avoid in patients with poor healing sites such as the lower leg, or use only under close supervision 2