From the FDA Drug Label
CLINICAL PHARMACOLOGY Salicylic acid has been shown to produce desquamation of the horny layer of skin while not effecting qualitative or quantitative changes in the structure of the viable epidermis. The mechanism of action has been attributed to a dissolution of intercellular cement substance
The FDA drug label does not answer the question.
From the Research
Salicylic acid resolves callus pain by gradually breaking down the thickened, hardened skin that forms calluses, and the most effective treatment regimen is applying topical salicylic acid in concentrations of 15-40% for 1-2 weeks, as supported by the study published in 2018 1. When applied topically, salicylic acid works as a keratolytic agent, meaning it softens and dissolves the protein keratin that makes up the callus. This occurs through two mechanisms: first, it increases the moisture content of the skin, making the hardened tissue softer and less painful; second, it dissolves the intercellular cement that holds the excess skin cells together. Some key points to consider when using salicylic acid for callus pain relief include:
- Apply salicylic acid products to clean, dry skin, protecting surrounding healthy skin with petroleum jelly.
- Gently file away the softened callus tissue with a pumice stone or foot file after treatment.
- Discontinue use if skin becomes irritated or inflamed, as salicylic acid can occasionally cause chemical burns if used improperly, especially in people with diabetes or poor circulation, as noted in the study published in 2014 2. The study published in 2018 1 provides the most recent and highest quality evidence for the effectiveness of salicylic acid in resolving callus pain, and its findings support the use of topical salicylic acid as a first-line treatment for callus pain. Other studies, such as the one published in 2016 3, have also investigated the efficacy of different treatments for plantar callus, but the 2018 study 1 provides the most relevant and up-to-date guidance for the use of salicylic acid in this context. It's also worth noting that the study published in 2011 4 found that a combination of tangential excision and topical cantharidin, which includes 30% salicylic acid, was effective in treating calluses, but the 2018 study 1 provides more specific guidance on the use of salicylic acid alone. Overall, the evidence suggests that salicylic acid is a safe and effective treatment for callus pain when used properly, and the most effective treatment regimen is applying topical salicylic acid in concentrations of 15-40% for 1-2 weeks, as supported by the study published in 2018 1.