A topical medication is a medication that is applied to a particular place on or in the body, as opposed to systemically. (The word topical derives from Greek τοπικός topikos, “of a place”.) Most often this means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments.
Many topical medications are epicutaneous, meaning that they are applied directly to the skin. Topical medications may also be inhalational, such as asthma medications, or applied to the surface of tissues other than the skin, such as eye drops applied to the conjunctiva, or ear drops placed in the ear, or medications applied to the surface of a tooth. As a route of administration, the topical route is contrasted with the enteral route (in the digestive tract), the intravenous route (injected into veins), and others.
A topical effect, in the pharmacodynamic sense, may refer to a local, rather than systemic, target for a medication. However, many topically administered drugs have systemic effects, because they reach the circulation after being absorbed by the tissues.
Topical medications differ from many other types of drugs because mishandling them can lead to certain complications in a patient or administrator of the drug.
Some hydrophobic chemicals, such as steroid hormones, can be absorbed into the body after being applied to the skin in the form of a cream, gel, or lotion. Transdermal patches have become a popular means of administering some drugs for birth control, hormone replacement therapy, and prevention of motion sickness. One example of an antibiotic that may be applied topically is chloramphenicol.