Patent medicines, also known as proprietary medicines, are non-prescription medicinal remedies that are trademarked and whose ingredients have been granted protection for exclusivity. The term "patent medicine" has become particularly associated with drug compounds manufactured during the eighteenth and nineteenth centuries. In actuality, the patent medicine recipes were not officially patented.

Most producers (often small family operations) used ingredients similar to those of their competitors—vegetable extracts with ample amounts of alcohol, morphine, opium, or cocaine. The recipes' contents were kept undisclosed to the public, and no governing body tested or approved effectiveness. By the middle of the nineteenth century, the manufacture of similar products had become a major industry in America. Remedies were available for almost any ailment.

Some physicians and medical societies were critical of patent medicines from the beginning. They argued that the remedies did not cure illnesses, discouraged the sick from seeking legitimate treatment, and caused alcohol and drug dependency.

The temperance movement of the late nineteenth century provided another voice of criticism, protesting the use of alcohol in medicines. By the end of the nineteenth century, Americans favored laws to force manufacturers to disclose their remedies' ingredients and use realistic language in their advertising. These laws met with fierce resistance from the manufacturers and the press, which had grown dependent on the money received from remedy advertising.

The Pure Food and Drug Act was passed by Congress in 1906, with strong support from President Theodore Roosevelt. It paved the way for public health action and consumer protection laws against unlabeled, unsafe, or ineffective ingredients and misleading or false advertising.