What it does

Opioids bind to receptors that regulate pain, mood, and breathing. They are effective medicines and also the substance class most likely to kill you when misused. The illicit supply in the US is now dominated by fentanyl, which is potent in specks and unevenly mixed.

Safer-use principles

• —Carry naloxone (Narcan) and make sure someone with you knows how to use it.
• —Never use alone. Overdose typically kills by stopping breathing over minutes — a bystander can save your life.
• —Assume any unregulated powder or pill contains fentanyl. Test with fentanyl strips; a negative result reduces but does not remove risk.
• —Tolerance drops fast after any break — days off, jail, hospital, detox. Returning to your old amount is a leading cause of fatal overdose.

Dangerous combinations

Opioids + any other depressant (alcohol, benzodiazepines, GHB, gabapentinoids) sharply raises the chance breathing stops. Opioids + stimulants ('speedball') masks the opioid until the stimulant wears off, then kills.

If something goes wrong

Slow or stopped breathing, blue/gray lips or fingertips, unresponsive, snoring/gurgling — call 911 and give naloxone. Give a second dose if no response in 2–3 minutes. Rescue breaths if trained. Stay until help arrives. Good Samaritan laws in most US states protect callers.