Creams, the most commonly used preparations, are emulsions of oil in water. They're easy to apply and appear to vanish when rubbed into the skin. Lotions are similar to creams but contain more water. They're actually suspensions of finely dispersed powdered material in a base of water or oil and water. Lotions are easy to apply and are particularly useful for cooling or drying the skin.
Solutions are liquids in which a drug is dissolved.
Solutions tend to dry rather than moisturize the skin. The most commonly used liquids are alcohol, propylene glycol, polyethylene glycol, and plain water. Powders may be incorporated into protective creams, lotions, and ointments. Gels are water-based substances thickened without oil or fat. The skin doesn't absorb gels as well as it absorbs preparations containing oil or fat.