Salicylic acid is a keratolytic. It belongs to the same class of drugs as aspirin (salicylates). It works by increasing the amount of moisture in the skin and dissolving the substance that causes the skin cells to stick together. May 15, · 1. Med Klin (Munich). May 15;82(11) [Treatment of anal fissures by oral administration of 5-amino-salicylic acid]. [Article in German]. anal fissure (fissure in ano) a (6% benzoic acid + 3% salicylic acid) that have shown that Diltiazem is very effective in treating patients with anal fissures.