Warning letters issued by the FDA recently to firms that marketed hair care products with claims such as restoration of hair growth and hair loss prevention illustrate an important distinction between the legal definitions of cosmetics and drugs. Warning letters officially inform companies that they may be engaged in illegal activities, and instruct manufacturers on how to bring their products into compliance with the law. Hair growers and hair loss prevention products, because of their mechanism of action, are considered drugs, not cosmetics, and these firms were not meeting the legal requirements for marketing a drug.

Unlike drugs and medical devices, neither cosmetic products nor cosmetic ingredients are reviewed or approved by the FDA before they are sold to the public. The agency only acts against cosmetic products found to cause harm after they are on the market.

Cosmetics or Drugs?

Much confusion exists about the status of cosmetic products having medicinal or drug-like benefits, says Linda Katz, M.D., M.P.H., director of the FDA's Office of Cosmetics and Colors. Although the FDA does not consider the term "cosmeceutical" to be a valid product class, Katz says it is used throughout the cosmetic industry to describe products that are marketed as cosmetics but that have drug-like effects. Tretinoin (retinoic acid), the biologically active form of vitamin A, for