Salicylic acid ointment

Salicylic acid, a beta-hydroxy acid (BHA), is a well-known exfoliant that targets the stratum corneum, the outermost layer of the skin. It helps loosen this layer and promotes healthy, natural skin renewal. Because it has low solubility in water, incorporating it into aqueous formulations can be challenging. However, a highly concentrated ointment base can be prepared easily using just two simple and inexpensive raw materials.

10% salicylic acid ointment formula:

Grind 10 g of salicylic acid thoroughly with 5 g of white mineral oil and 10 g of vaseline (petrolatum) on a glass slab. After the mixture becomes uniform with no visible crystals, add another 25 g of vaseline and mix again until smooth. Finally, incorporate the remaining 50 g of vaseline and blend thoroughly. This stepwise process, known as geometric dilution, is a standard pharmaceutical technique used when preparing oleaginous ointments or creams.

For a less concentrated salicylic acid ointment base, simply reduce the amounts of salicylic acid and white mineral oil while increasing the proportion of vaseline (petrolatum) as follows: