Improper use of these medications, however, can be dangerous. The sale of nonprescription drugs, vitamins, and herbal dietary supplements is a multi-billion dollar industry. In foolish hands, medicine is a poison.' Such is the case with over-the-counter (OTC) drugs-those medicines found on shelves in drugstores, convenience stores, and supermarkets. The Italian adventurer Casanova (1725–1798) is often quoted as saying: 'In wise hands, poison is medicine. The following entry attempts to provide as much relevant information as possible for the scope and intended audience of this encyclopedia. Volumes could be written on the use and abuse of OTC medications. Herbal dietary supplements and vitamins are also sold over the counter.

Other ailments that are relieved by OTC drugs include insomnia (having difficulty falling asleep or being unable to fall asleep) motion sickness nausea (an upset stomach, sometimes combined with vomiting) and obesity (being extremely overweight). OTC drugs are also commonly used to remedy coughs and sore throats, constipation (the inability to have a bowel movement), and diarrhea (loose, watery, or frequent bowel movements). The most common OTC medications are used to treat aches and pains, allergies, drowsiness, and cold and influenza (flu) symptoms. Over-the-counter (OTC) medicines are preparations that are sold to consumers without a doctor's prescription.

Over the counter drugs