The meaning of DRUG is a substance used as a medication or in the preparation of medication. How to use drug in a sentence. Drug addiction, also called substance use disorder, is a disease that affects a person's brain and behavior and leads to an inability to control the use of a legal or illegal drug or medicine. Substances such as alcohol, marijuana and nicotine also are considered drugs. Use our drug interaction checker to find potentially harmful drug, food, and alcohol interactions. Type a drug name in the box above to get started. Not all drugs interact, and not every interaction means you must stop taking one of your medications. 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. 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. 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. 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. 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. Learn how to properly get rid of unused or expired medication.