Lotions are solutions, but may also be suspensions or emulsions, that are intended to be applied to the skin without friction on a carrier fabric such as lint and covered with a waterproof dressing. In some cases lotions are applied to the scalp, where the vehicle for the medication is alcohol based, allowing for rapid drying of the hair and thus making the product more acceptable to the patient (e.g. Salicylic Acid Lotion2% BPC). In these cases, problems of flammability are addressed by suitable labelling.
A liniment is a liquid preparation intended to be rubbed with friction and massaged onto the skin to obtain analgesic, rubefacient or generally stimulating effects. Liniments should not be used on broken skin. They are usually solutions of oils, alcohols or soaps, but may be formulated as emulsions.
Applications are solutions, though they may also be suspensions or emulsions, intended to be applied without friction to the skin and to be used without any dressing or covering material.
These are principally solutions of pyroxylin in a vehicle of ether and alcohol that are intended to be painted onto the skin and left to dry. When dry, the collodion leaves a flexible film of cellulose on the skin which may be used to seal minor injuries or retain a dissolved drug in contact with the skin for an extended period. Collodions are highly volatile and highly flammable and care should be taken to label any preparation appropriately.