In determining whether a prescription medication should be granted OTC status, the risks and benefits of treatment with the medication must be weighed. Ultimately, the decision must be made with some degree of uncertainty. Pharmacists must take advantage of this uncertainty to demonstrate their professional expertise and value to society. The Rx-to-OTC switch for H2-blockers may benefit many, although not all, patients with acid peptic complaints, and it offers pharmacists an opportunity to demonstrate their willingness and ability to assist in the use of cost-effective OTC drug therapy.