Whitfield's Ointment is salicylic acid

Salicylic acid

Salicylic acid is a monohydroxybenzoic acid, a type of phenolic acid and a beta hydroxy acid. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin...

 and benzoic acid

Benzoic acid

Benzoic acid , C7H6O2 , is a colorless crystalline solid and the simplest aromatic carboxylic acid. The name derived from gum benzoin, which was for a long time the only source for benzoic acid. Its salts are used as a food preservative and benzoic acid is an important precursor for the synthesis...

 in a suitable base, such as lanolin

Lanolin

Lanolin , also called Adeps Lanae, wool wax or wool grease, is a yellow waxy substance secreted by the sebaceous glands of wool-bearing animals. Most lanolin used by humans comes from domestic sheep...

 or vaseline

Vaseline

Vaseline is a brand of petroleum jelly based products owned by Anglo-Dutch company Unilever. Products include plain petroleum jelly and a selection of skin creams, soaps, lotions, cleansers, deodorants and personal lubricants....

.

The original ointment contains 3 % salicylic acid and 6 % benzoic acid, but other ratios are also used.
It is used for the treatment of fungal infections, such as athlete's foot.
It is cheap and effective and can have a slight burning effect that goes away after a few minutes.

It is named for Arthur Whitfield (1868–1947), a British dermatologist .