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. The meaning of DRUG is a substance used as a medication or in the preparation of medication. How to use drug in a sentence. 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. The mission of the Drug Enforcement Administration (DEA) is to ensure the safety and health of American communities by combating criminal drug networks bringing harm, violence, overdoses, and poisonings to the United States. 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. Find detailed information on prescription drugs, OTC medications, vitamins and dietary supplements, including their uses, side effects, and interactions. Misusing prescription medications — like Adderall®, Vicodin®, and Xanax® — can lead to lasting problems like addiction. Not to mention leaving you vulnerable to an overdose. 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. Drug and health information, from pharmacists you can trust. Browse A-Z: drugs, treatments, conditions, drug classes or symptoms. Drugs.com is the most popular, comprehensive and up-to-date source of drug information online.