Curanail nail lacquer is used to treat fungal infections affecting up to 2 nails and affecting the upper half or sides of the nail. The active substance in Curanail is amorolfine (as the hydrochloride) which belongs to a group of medicines known as antifungals. Curanail nail lacquer targets and kills the fungi which causes nail infections. Clearing up the fungal nail infections until the healthy nail has grown back.