Over-the-counter (OTC) drugs are medicines that may be sold without a prescription, in contrast to prescription drugs. The name "over-the-counter" is somewhat confusing to some, since these items can be found on the shelves of stores and bought like any other packaged product in some countries or in others may be bought "over the counter" from the pharmacy, while prescription drugs are sold at a pharmacy counter. The term likely dates back to before self service shopping became common, when most goods were obtained by requesting them from a clerk at a sales counter; while prescription drugs required a visit to the doctor first, these drugs could be purchased "over the (sales) counter" just like other goods. Some medicines considered safe in general terms may be available in general stores, supermarkets, gas stations etc. The rules vary considerably from country to country.
Thus, manufacture must be done either pursuant to an FDA monograph, which specifies types of OTC drugs, active ingredients and labeling requirements, or pursuant to a New Drug Application (NDA), for products which do not fit within a specific monograph. Because an NDA is extremely expensive to obtain, due primarily to testing requirements, most OTC substances produced in the USA are sunscreens, anti-microbial and anti-fungal products, external and internal analgesics such as lidocaine and aspirin, psoriasis and eczema topical treatments, anti-dandruff shampoos containing coal tar, and other topical products with a therapeutic effect.
The Federal Trade Commission regulates advertising of OTC products. This is in contrast to prescription drug advertising, which is regulated by the FDA.
Medication available only with a prescription is marked somewhere on the box/container with [POM]. Over-the-counter medicines are marked with [P]. A prescription is not required for [P] medicines and pharmacy sales assistants are required by law to ask certain questions, most of all, whether the patient is taking other medication, before selling these. It is with this information that the pharmacist can halt the sale, if need be. Some medication available in supermarkets and petrol stations is sold there only in smaller packet sizes. Often, larger packs will be marked as [P] and available only from a pharmacy. Frequently, customers buying larger than usual doses of [P] medicines (such as Paracetamol) will be queried, due to the possibility of abuse.
Over time, drugs that prove themselves safe and appropriate for self-medication, may be switched from prescription to OTC. An example of this is diphenhydramine (Benadryl) which once required a prescription but now is available OTC nearly everywhere. Diphenhydramine is a deliriant, nevertheless, most recreational drug users find its effects uncomfortable rather than exciting. More recent examples are cimetidine and loratadine in the United States, and ibuprofen (Herron Blue/Nurofen) in Australia.
It is somewhat unusual for an OTC drug to be withdrawn from the market as a result of safety concerns, rather than market forces, though it does happen occasionally, phenylpropanolamine being one example.
Recently many U.S. drugstores have begun moving products containing pseudoephedrine into locations where customers must ask a pharmacist for them. A prescription is not required; the change is allegedly being made in an effort to reduce methamphetamine production. Since the passage of the Methamphetamine Precursor Control Act, the purchase of pseudoephedrine in the United States is restricted and the identity of the purchaser is required to be obtained and recorded. In addition, pseudoephedrine itself is a mild stimulant- somewhere between caffeine and ephedrine. Nonetheless, these products are still considered OTC since no prescription is required.