Opioids are a class of drugs that reduce pain and, at higher amounts, produce a sense of euphoria — by acting on specific receptors in the brain and body that naturally respond to the body’s own pain-relieving chemicals.
Where opioids come from
- Natural: derived directly from the opium poppy — morphine and codeine
- Semi-synthetic: chemically modified from natural opioids — oxycodone, hydrocodone, heroin
- Fully synthetic: built from scratch in a lab, not derived from the poppy plant at all — fentanyl, methadone, tramadol
All three categories act on the same receptors and carry the same fundamental risks, regardless of whether they’re a prescription pill, a street drug, or both at once (a growing number of counterfeit pills contain fentanyl without the person knowing).
What opioids do in the body
They bind to opioid receptors — mainly a type called mu-opioid receptors — found throughout the brain, spinal cord, and gut. This produces pain relief, but also slows breathing, which is the mechanism behind every opioid overdose death. This is also why combining opioids with anything else that slows breathing (alcohol, benzodiazepines, other sedatives) is especially dangerous.
Legal status doesn’t equal safety
A prescription opioid from a pharmacy and an opioid bought on the street carry different legal status but not necessarily different physical risk — both act on the same receptors, and both can lead to physical dependence with regular use. The main practical safety difference is that a prescription is dose-consistent and regulated; an illicit supply is not, and today is very likely to contain fentanyl regardless of what it’s sold as.
Where to go from here
If you’re trying to understand your own or someone else’s situation, our guide on [physical dependence vs. addiction] explains a distinction that changes how this information applies to you. If you’re looking for immediate help: call or text 988 for crisis support, or 1-800-662-4357 (SAMHSA National Helpline) for treatment options.
Medically reviewed by [pending]. Sources: NIDA, CDC.