A drug is any substance that causes a change in how people feel mentally, emotionally, or physically. Mood and other brain processes such as perception, attention, learning, memory, concentration, and abstract thought can be impacted.
Drug and their effects depend on many factors, including dose, types of drugs used and their interaction, how the drug is taken, and the body’s response to drugs that develop over time (tolerance, dependence, etc.)
Drugs include legal drugs (such as alcohol, tobacco, prescription drugs such as anti-depressants and painkillers) and illegal drugs such as cocaine, speed, and LSD. When discussing drugs, it can be helpful to categorize drugs according to their effect on one’s mind and body.