Transdermal is a term used to describe a drug delivery system that is administered through the skin. Synonyms for transdermal include transcutaneous, percutaneous, dermal, and skin-adhesive. These terms refer to the same method of drug delivery through the skin, but may be used in different contexts or with different formulations. Transdermal patches, for example, use a skin-adhesive to deliver medication over a period of time. Percutaneous medications may be delivered by injection or other methods, and may be absorbed through the skin or other tissues. Overall, the use of transdermal medication can offer many advantages over other methods of administration, including improved safety and convenience.