lotion
A lotion is a thin, pourable liquid you dab or paint onto the skin and let dry, rather than rub in — the watery counterpart to a thick cream. Because it is fluid and is applied without friction, it suits inflamed or tender skin that you do not want to massage.
Pharmaceutically a lotion is a fluid topical preparation meant to be applied to the skin without rubbing. It may be a true solution, a suspension (a “shake lotion” such as calamine, which leaves a fine powder behind as the water evaporates) or a fluid emulsion. As the water phase evaporates it produces a cooling effect and deposits the active ingredient on the surface.
Lotions cover large or hairy areas easily and feel light and non-greasy, which favours patient acceptance. The flip side is short contact time and limited occlusion: the thin film and evaporating vehicle mean the drug stays on the skin only briefly, so lotions are better for soothing, cooling and surface action than for deep or prolonged delivery, and suspension lotions must be shaken before each use.
Calamine lotion is a pink aqueous suspension dabbed onto itchy, irritated skin; as the water dries it leaves a cooling, soothing powder layer behind.
A fluid preparation dabbed on, not rubbed in, cools the skin as it dries.
A shake lotion such as calamine leaves a protective powder film as its water evaporates, giving a cooling, drying effect — the opposite of an occlusive ointment.