Synthol was developed by Maurice Bunau-Varilla, a prominent newspaper publisher of the early twentieth century, as a tonic.

[2] Formerly the formula consisted 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(s).

Following a rupture in supply 2014–2015[3] the product returned to French pharmacies in June 2016 with the same composition, minus chloral hydrate, now banned, and with the indication "mouthwash" («bain de bouche») removed.

[4] Among the new uses of the reformulation is endorsement of the Synthol gel as an umbilical cord antiseptic.