A drug is any substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhalation, injection, smoking, ingestion, absorption via a patch on the skin, suppository, or dissolution under the tongue. Aspirin tablets consist of acetylsalicylic acid and are often used to treat pain, fever, and inflammation. In pharmacology, a drug is a chemical substance that produces a biological effect when administered to a living organism. Pharmaceutical drugs are used to treat, cure, prevent, or diagnose diseases and promote well-being.