A prescription drug (or POM Prescription Only Medicine, in UK) is a licensed medicine that is regulated by legislation to require a prescription before it can be obtained. The term is used to distinguish it from over the counter drugs which can be obtained without a prescription. Different jurisdictions have different definitions of what constitutes a prescription drug. As a general rule, over the counter drugs are used to treat conditions not necessarily requiring a doctor's care and will have been proven to meet higher safety standards for self-medication by patients. Often a lower dosage of a drug will be approved for OTC use, while higher dosages will remain the province of a doctor's prescription; a notable case is ibuprofen, which has been widely available as an OTC pain killer since the mid-1980s but is still available in doses up to four times the OTC dose for use in cases of severe orthopedic pain.

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