Synthol is a mouthwash, hair product and tonic, available in France since 1925. Synthol was developed by Maurice Bunau-Varilla, a prominent newspaper publisher of the early twentieth century. He promoted it as a cure-all tonic.
The formula consists of chloral hydrate, menthol, veratrol, resorcinol and salicylic acid. Sold mainly as a mouthwash, in a distinctive black carton, it is also packaged as a gel and spray for the treatment of muscular pain.