They act by being absorbed into the skin and attract water from atmosphere and serve as a reservoir for the stratum corneum. Commonly used humectants are propylene glycol and glycerin. Liniments Are viscous liquids containing substances possessing analgesic, soothing or stimulating properties when applied on the skin. They are usually made with a base of oil, alcohol, or soap solutions, e.g., methyl salicylate liniment. Liniments should not be applied to broken skin.
Lotions Are aqueous solutions or suspensions that cool diffusely inflamed unbroken skin.
They cool by evaporation and should be applied frequently. Lotions are also used to apply drugs to the skin when only a thin layer of the preparation is intended to apply over a large surface area. In addition to cooling, they leave a deposit of inert powder on the skin surface. The most commonly used ointment bases consist of soft paraffin or a combination of soft paraffin with liquid paraffin and hard paraffin. Due to their anhydrous nature ointments do not require any preservatives.