A drug is any chemical substance that affects the functioning of living things and the organisms (such as bacteria, fungi, and viruses) that infect them. Find detailed information on prescription drugs, OTC medications, vitamins and dietary supplements, including their uses, side effects, and interactions. Detailed and accurate information is provided on over 24,000 prescription and over-the-counter medicines for both consumers and healthcare professionals. Psychoactive substances are used across cultures for purposes ranging from medicinal and therapeutic treatment of mental disorders and pain, to performance enhancement. Their effects are influenced by the drug itself, the environment, and individual factors. The meaning of DRUG is a substance used as a medication or in the preparation of medication. How to use drug in a sentence. Drugs.com is the most popular, comprehensive and up-to-date source of drug information online. Providing free, peer-reviewed, accurate and independent data on more than 24,000 prescription drugs, over-the-counter medicines & natural products. Recreational drug use is the use of a drug (legal, controlled, or illegal) with the primary intention of altering the state of consciousness through alteration of the central nervous system in order to create positive emotions and feelings. Learn about the side effects, dosages, and interactions of prescription drugs, over-the-counter medicines, herbs, and supplements. Drugs A to Z gives basic information on drugs with addictive potential, including how they are used, how they make people feel, and their health effects, including risk for substance use disorder. Treatment options for substance use disorders related to these drugs are also included. Learn how to properly get rid of unused or expired medication.