In May 1972, FDA applied the principle of a retrospective review to over-the-counter (OTC) drugs. The structure for this OTC review would necessarily be different than that of the prescription drug review, mainly because of the vast array of available OTC products -- hundreds of thousands of different preparations. The OTC review focused on active ingredients, around 1,000 different items, and panels of experts were convened to evaluate these drugs. The agency would publish the results as a series of monographs in the Code of Federal Regulations, specifying the active ingredients, restrictions on formulations, and labeling by therapeutic category.

FDA formed seventeen panels, consisting of seven voting members (medical, dental, and scientific experts) and non-voting representatives for industry and consumers. The panels were responsible for arranging the drugs into three categories: safe and effective, unsafe and/or ineffective (which should no longer be marketed), and probably safe and effective but needing further testing to establish significant proof. The review is ongoing. The agency eventually decided that drugs in the last category, like those in the second, would be taken off the market until sufficient proof dictated otherwise.