Amlodipine in the context of "Vasodilation"

Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescription. In many countries, OTC drugs are selected by a regulatory agency to ensure that they contain ingredients that are safe and effective when used without a physician's care. OTC drugs are usually regulated according to their active pharmaceutical ingredient (API) and strengths of final products.

The term over-the-counter (OTC) refers to a medication that can be purchased without a medical prescription. In contrast, prescription drugs require a prescription from a doctor or other health care professional and should only be used by the prescribed individual. Some drugs may be legally classified as over-the-counter (i.e. no prescription is required), but may only be dispensed by a pharmacist after an assessment of the patient's needs or the provision of patient education. Regulations detailing the establishments where drugs may be sold, who is authorized to dispense them, and whether a prescription is required vary considerably from country to country.