Systemic medications are taken by mouth or injected and are distributed throughout the body. Applying the wrong medication may worsen a skin condition or may mask symptoms, making the diagnosis difficult for a doctor. Thus, the formulation and consistency vary among topical preparations. Depending on the vehicle used, the preparation will be an ointment, cream, lotion, solution, powder, or gel. Ointments, which contain a lot of thick oil and very little water, feel greasy and are difficult to wash off.
Ointments are most appropriate when the skin needs lubrication or moisture.
Although messier to use than water-based cream preparations, ointments are usually better at delivering active ingredients into the skin. 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.