Salonpas pain relief patch medicated plaster is used for the symptomatic relief of pain of muscles and joints associated with strains and sprains how to use clean and dry the affected area before applying the plaster remove the plastic film and apply the adhesive part directly to the skin apply 1 plaster to the affected area and leave in place for up to 8 to 12 hours if pain recurs 8 12 hours after applying the first plaster a second plaster can be applied only use one plaster at a time