The word drug has two main meanings:

1. A medicine or substance used to treat illness, relieve pain, or improve health. When you have a headache, you might take a pain-relief drug like ibuprofen. Doctors prescribe drugs to fight infections, control diseases like diabetes, or help with countless other health problems. Pharmacies stock thousands of different drugs, each designed to help the body in specific ways. The development of antibiotics, vaccines, and other drugs has saved millions of lives and transformed medicine.
2. A substance that affects how your brain and body work, and that can sometimes be harmful or dangerous. Drug addiction is a serious medical problem that hurts individuals and families. When people talk about the drug trade or drug abuse, they're usually referring to this second meaning.

The challenge with the word drug is that context matters enormously. Insulin is a lifesaving drug for people with diabetes. Chemotherapy drugs help fight cancer. But other drugs destroy lives. Understanding this distinction helps explain why some drugs require prescriptions from doctors who understand both their benefits and risks.

As a verb, to drug means to give someone a drug. This can be helpful, like drugging a patient with anesthesia before surgery, or harmful and illegal, like drugging someone without their knowledge.