Teens have a lot of questions about drugs, which is why NIDA holds an annual Drug Facts Chat Day to explain the science behind drug abuse. At the last Chat Day, “casa grande” from Casa Grande Union High School in Arizona asked: What are opioids?

Opioids, also known as “opiates,” are a class of drugs with powerful pain-relieving properties. So, some are prescribed by doctors like Percocet, Vicodin, and codeine for people who need them. But then there are also street drugs like heroin that are also opioids—so yeah, Vicodin and heroin are in the same class of drugs!

When prescribed by a doctor, opioids can be used in a responsible way to reduce pain, treat diarrhea, or control coughing. Inside our bodies, opioids link to receptors in the brain, spinal cord, and gut, much like pieces in a puzzle. When they do, they can block the experience of pain. For example, morphine is sometimes given to people before or after surgery. However, opioids can also affect parts of the brain that control feelings of pleasure, producing a sense of euphoria that makes people want to take them again and again even when they’re not in pain. When people keep taking them like that, opioids can actually change the way the brain works, causing strong cravings that are of part of having an addiction.