Salicylic acid is used as a medicine to help remove the outer layer of the skin. As such it is used to treat warts, calluses, psoriasis, dandruff, acne, ringworm, and ichthyosis.
For conditions other than warts, it is often used together with other medications. It is applied to the area affected.
Description: Organic beta hydroxy acid (chemical name: 2-hydroxybenzoic acid), occurs naturally in various plants. Fine, white powder, odorless. USP grade. Solubility: see below. pH Value: 2.4. Melting Point: 159°C (318°F).
Water: about 0.2% at 20oC, about 1.7% at 75oC (by adding about 5% of sodium phosphate or another neutral salt, solubility of salicylic acid in water is increased to about 1.8%)
Alcohol (ethanol): about 14% in pure ethanol, about 0.5% in 20% ethanol
Propylene glycol: about 3-6%
Glycerin: about 1.6%
Octyldodecanol: about 15-20%
Use: Typical use level 0.5-3%. Typically, it is added to the water phase of formulas but it is only slightly soluble in water. If used at concentrations higher than 2%, octyldodecanol or propylene glycol should be used as solvent. Salicylic acid can be added also in powder form to a finished cream or lotion without dissolving it first in water or another solvent.
Applications: Peels and exfoliant products. Anti-acne products (max. 2%). Anti-dandruff products (max 3%). Wart-removing products (max. concentration depends on type of plaster vehicle used).