Opioid · morphinan
Opioids
aka Opiates · Pain pills · Painkillers · Narcotics · Codeine · Oxycodone · Hydrocodone · Morphine · Fentanyl · Tramadol · Heroin
Last verified
Opioids are the most clinically important class of analgesics in medicine and the single largest contributor to drug-overdose mortality in North America and increasing parts of Europe. They work by binding mu-, delta- and kappa-opioid receptors in the central nervous system, producing analgesia, anxiolysis, euphoria, sedation, respiratory depression and reduced gut motility. The class spans natural opium alkaloids (morphine, codeine), semi-synthetic derivatives (heroin, oxycodone, hydrocodone, buprenorphine), full synthetics (fentanyl, methadone) and atypical compounds with mixed mechanisms (tramadol, tapentadol).
The actual cause of opioid overdose death is respiratory depression — the brainstem's breathing reflex is suppressed until breathing slows and stops. Pure-opioid overdose is reversible with naloxone (Narcan) if given in time. The fatal scenarios almost always involve combination with another CNS depressant — benzodiazepines, alcohol, GHB/GBL, gabapentinoids, barbiturates — or contamination of the supply with fentanyl-class analogues 50-100x more potent than the drug the user intended to take.
The defining feature of the opioid landscape in 2026 is fentanyl contamination. Counterfeit "M30" oxycodone pressings from Sinaloa-affiliated operations now appear at industrial scale and contain unpredictable fentanyl doses. Heroin supplies in North America are largely fentanyl by mass; European heroin markets are following. Pressed "Xanax bars" routinely contain fentanyl. The single biggest harm-reduction tool today is the fentanyl test strip, an immunoassay that costs about a euro, takes 30 seconds, and has been independently shown to reduce overdose mortality in cohorts that use it consistently.
Major compounds at a glance
| Compound | Brand examples | Potency vs morphine | Half-life | Notes |
|---|---|---|---|---|
| Codeine | Solpadeine, Co-codamol, Tylenol-3 | ~0.1x | 3 h | Weak, oral, works via CYP2D6 → morphine |
| Tramadol | Ultram, Tramal | ~0.1x | 6 h | Atypical (opioid + SNRI); seizure & serotonin risks |
| Hydrocodone | Vicodin, Norco | ~1x | 4 h | Usually combined with paracetamol |
| Morphine | MS Contin, Sevredol | 1x (reference) | 3 h | Class reference; gold-standard analgesic |
| Oxycodone | OxyContin, Roxicodone, Percocet, M30 | ~1.5x | 4 h | At centre of US opioid epidemic; counterfeit M30s are the main fentanyl vector |
| Heroin | (illicit) | ~2-3x | 30 min | Lipophilic, fast-acting; supply increasingly fentanyl-laced |
| Methadone | Dolophine, Subutex (combo) | ~1x oral | 24-48 h | Long-acting; gold-standard OUD treatment |
| Buprenorphine | Subutex, Suboxone | partial agonist | 24-36 h | Ceiling on respiratory effect; safer for OUD treatment |
| Fentanyl | Duragesic, Actiq | 50-100x | 1-2 h IV / 17 h patch | Main driver of overdose deaths; in most counterfeit pills |
For specific compounds with deep coverage, see: heroin, tramadol. For the most-dangerous interaction class, see benzodiazepines.
Harm reduction
- Test what you have. Fentanyl strips are non-negotiable for any non-pharmacy opioid. Crush a small portion, dissolve in water, dip the strip. Two lines means no fentanyl detected (still test the next batch); one line means fentanyl present.
- Naloxone (Narcan) lives in your bag, not in a drawer. Two doses minimum. If you live with or near other people who use, brief them on what overdose looks like (pinpoint pupils, slow or absent breathing, unresponsive) and on how to administer naloxone.
- Never combine with benzodiazepines or alcohol. This combination drives the majority of polysubstance opioid deaths. The two depress breathing through different mechanisms and the effects stack non-linearly.
- Never use alone. "Never use alone" hotlines stay on the line while you use and call for help if you stop responding. US: 1-800-484-3731. Canada: 1-888-688-NORS. Europe: contact your local user union or harm-reduction service.
- Tolerance resets fast. Three days off, illness, jail or a detox attempt drops your tolerance significantly. The dose that was fine a week ago can stop your breathing today. Halve it. Halve it again if you've been out for two weeks.
- Recovery position for anyone breathing but unresponsive. On their side, head supported, mouth tilted down. Stay until they are talking and standing.
- If you inject: sterile water, fresh needle every time, alcohol swab, rotate sites, never share filters or cookers, count seconds when you push. Pharmacies in most European countries dispense needles free.
- If you're trying to stop: medication-assisted treatment (methadone, buprenorphine/Suboxone) is the most-evidenced treatment in addiction medicine. It is not "swapping one drug for another" — it is the difference between living and not. Your GP or any addiction service can refer you.
- For families and friends: carry naloxone. Take a 20-minute training. The person you're worried about probably won't ask for it; just have it on you.
Dosage.
Oral
- Threshold
- 5 mg
- Light
- 10–30 mg
- Common
- 30–60 mg
- Strong
- 60–120 mg
- Heavy
- 120 mg
Insufflated
- Threshold
- 5 mg
- Light
- 5–20 mg
- Common
- 20–40 mg
- Strong
- 40–80 mg
- Heavy
- 80 mg
| Route | Threshold | Light | Common | Strong | Heavy |
|---|---|---|---|---|---|
| Oral | 5 mg | 10–30 mg | 30–60 mg | 60–120 mg | 120 mg |
| Insufflated | 5 mg | 5–20 mg | 20–40 mg | 40–80 mg | 80 mg |
Start at the bottom. Body chemistry, tolerance, and combinations all matter.
Duration.
Oral
total ~ 1320 min- Onset
- 15–60 min
- Peak
- 60–180 min
- Offset
- 3–6h
- After
- 4–12h
Insufflated
total ~ 640 min- Onset
- 1–10 min
- Peak
- 30–90 min
- Offset
- 1.5–3h
- After
- 3–6h
Effects.
Positive
- Strong analgesia (the original clinical use)
- Profound anxiolysis and "warm" euphoria
- Pleasant drowsiness without full sedation at moderate doses
- Cough suppression
- Sense of physical contentment
Neutral
- Pinpoint pupils (miosis)
- Slowed breathing
- Reduced bowel motility (constipation)
- Pruritus (itching), particularly facial
- Decreased libido with regular use
Negative
- Respiratory depression — the actual cause of overdose deaths
- Rapid tolerance and dose escalation
- Physical dependence within 1-2 weeks of daily use
- Severe withdrawal (cramps, RLS, sweats, mood crash, insomnia for days)
- Counterfeit pills containing fentanyl drive most current overdose deaths
- Long-term cognitive blunting with chronic heavy use
Interactions.
Heads up
Many drug combinations are unsafe even at low doses. When in doubt, take less or abstain. Always cross-check with the interaction checker tool.
Dangerous
Combination may cause serious harm. Avoid.
- benzodiazepines
- alcohol
- ghb
- gbl
- barbiturates
- gabapentinoids
- other-opioids
Unsafe
Substantial risk. Combination not recommended.
- amphetamine
- cocaine
- methamphetamine
- dxm
Caution
Mild interaction. Use with reduced doses.
- cannabis
- ketamine
- ssris
- mdma
Testing.
- ReagentFentanyl-stripExpected reactionSTRONGLY RECOMMENDED before every batch from any non-pharmacy source. Strips test for fentanyl-class analogues and are the single biggest harm-reduction tool for opioids today. Counterfeit pressed M30s and pressed "Xanax bars" routinely contain fentanyl.
- ReagentMarquisExpected reactionPurple (consistent with morphinan family; reagent does not measure purity or detect fentanyl)
- ReagentMeckeExpected reactionBlue-green to dark green
- ReagentMandelinExpected reactionBrown to black for morphinan opioids; tramadol gives no reaction
- ReagentOpioid-immunoassayExpected reactionStandard 5-panel opiate tests detect morphine, codeine and heroin metabolites. Oxycodone, fentanyl, methadone, buprenorphine and tramadol require dedicated assays or extended panels.
| Reagent | Expected reaction |
|---|---|
| Fentanyl-strip | STRONGLY RECOMMENDED before every batch from any non-pharmacy source. Strips test for fentanyl-class analogues and are the single biggest harm-reduction tool for opioids today. Counterfeit pressed M30s and pressed "Xanax bars" routinely contain fentanyl. |
| Marquis | Purple (consistent with morphinan family; reagent does not measure purity or detect fentanyl) |
| Mecke | Blue-green to dark green |
| Mandelin | Brown to black for morphinan opioids; tramadol gives no reaction |
| Opioid-immunoassay | Standard 5-panel opiate tests detect morphine, codeine and heroin metabolites. Oxycodone, fentanyl, methadone, buprenorphine and tramadol require dedicated assays or extended panels. |
Cross-check with a secondary reagent. Tests tell you what something isn't, not always what it is.
Legal status.
- DEGermanyprescription-only-btmg
- ATAustriaprescription-only-btmg
- CHSwitzerlandprescription-only
- NLNetherlandsprescription-only-opium-act
- BEBelgiumprescription-only
- LULuxembourgprescription-only
- FRFranceprescription-only
- ESSpainprescription-only
- PTPortugalprescription-only
- ITItalyprescription-only
- PLPolandprescription-only
- CZCzechiaprescription-only
- SESwedenprescription-only
- DKDenmarkprescription-only
- NONorwayprescription-only
- FIFinlandprescription-only
- IEIrelandclass-a-to-c
- UKUnited Kingdomclass-a-to-c
- USUnited Statesschedule-2-to-5
- CACanadaschedule-1-to-5
- AUAustraliaschedule-8
- TRTurkeyprescription-only
| Country | Status |
|---|---|
| DEGermany | prescription-only-btmg |
| ATAustria | prescription-only-btmg |
| CHSwitzerland | prescription-only |
| NLNetherlands | prescription-only-opium-act |
| BEBelgium | prescription-only |
| LULuxembourg | prescription-only |
| FRFrance | prescription-only |
| ESSpain | prescription-only |
| PTPortugal | prescription-only |
| ITItaly | prescription-only |
| PLPoland | prescription-only |
| CZCzechia | prescription-only |
| SESweden | prescription-only |
| DKDenmark | prescription-only |
| NONorway | prescription-only |
| FIFinland | prescription-only |
| IEIreland | class-a-to-c |
| UKUnited Kingdom | class-a-to-c |
| USUnited States | schedule-2-to-5 |
| CACanada | schedule-1-to-5 |
| AUAustralia | schedule-8 |
| TRTurkey | prescription-only |
Information, not legal advice. Status varies by region and changes over time.
FAQ.
What are opioids?
A class of drugs that bind to opioid receptors (mu, delta, kappa) in the central nervous system to produce analgesia, anxiolysis and euphoria. The class includes natural opium alkaloids (morphine, codeine), semi-synthetic derivatives (heroin, oxycodone, hydrocodone, buprenorphine), synthetic morphine analogues (fentanyl, methadone) and atypical compounds with mixed mechanisms (tramadol, tapentadol).
How do opioids differ from each other?
Mainly in potency, route, duration and how cleanly they hit the mu-opioid receptor. Codeine is weak, oral-only and works through metabolic conversion to morphine. Oxycodone is roughly 1.5x morphine and orally bioavailable. Heroin is fast-acting and lipophilic, making it efficient by any route. Fentanyl is 50-100x morphine, often dosed in micrograms. Tramadol is atypical — a weak opioid plus an SNRI, with serotonin syndrome and seizure risks pure opioids don't have.
What is the fentanyl problem?
Fentanyl is a synthetic opioid 50-100x more potent than morphine. It can be produced cheaply and is increasingly pressed into counterfeit pills sold as oxycodone (the infamous "M30" blue tablets), pressed Xanax bars, and mixed into heroin supplies. The vast majority of US opioid deaths since 2017 involve fentanyl, often unknown to the user. Fentanyl test strips, used correctly, catch this; they cost about €1 each and have measurably reduced overdose mortality wherever distributed at scale.
How do opioids kill people?
Respiratory depression. Opioids suppress the brainstem's breathing reflex; at high enough doses, breathing slows and stops. The lethal interactions are with other CNS depressants — benzodiazepines, alcohol, GHB/GBL, gabapentinoids, barbiturates — which compound the effect non-linearly. Pure-opioid overdose is reversible with naloxone (Narcan) if given in time. Combination overdose may need multiple doses and intensive support.
What is naloxone (Narcan) and how do I get it?
An opioid antagonist that displaces opioids from receptors and reverses overdose within minutes. Available as a nasal spray or intramuscular injection. In most US states and many EU countries it's available over the counter or via free distribution programs (NEXT Distro, harm-reduction services, some pharmacies). If you use opioids or know someone who does, carry it. Multiple doses may be needed for fentanyl-involved overdoses. Read the [overdose response guide](/safety/opioid-overdose-response).
Are opioids addictive?
Among the most aggressively addictive substances in medicine. Physical dependence develops within 1-2 weeks of daily use; psychological reinforcement is strong; tolerance escalates rapidly. The reward signal from a clean opioid hit is consistently rated as one of the most reinforcing in subjective experience reports, which is why supply-side interventions alone (restricting prescriptions) have repeatedly driven users toward more dangerous substitutes (heroin, fentanyl) rather than abstinence.
What is opioid withdrawal like?
Not directly fatal (unlike benzo or alcohol withdrawal) but profoundly unpleasant. Classical symptoms — restless legs, gooseflesh, dilated pupils, runny nose, sweating, GI cramping and diarrhoea, severe anxiety, insomnia, mood crash. Onset 8-24 hours after last dose (sooner for short-acting drugs like heroin, later for methadone), peak 2-5 days, with residual mood and energy symptoms for weeks. Medication-assisted treatment (buprenorphine, methadone) dramatically reduces severity and overdose mortality compared to abstinence-only approaches.
Tramadol vs codeine — which is stronger?
They sit at roughly similar analgesic potency but work very differently. Codeine is a pure opioid that gets metabolised to morphine via CYP2D6 (with massive individual variability). Tramadol is a weak opioid plus an SNRI, which adds serotonin-syndrome risk and seizure risk that codeine doesn't carry. Codeine has the more "classical" opioid feel; tramadol can be mildly stimulating before sedation kicks in. See the [tramadol page](/substances/tramadol) for more.
Oxycodone vs hydrocodone — what's the difference?
Both are semi-synthetic opioids from thebaine, both schedule-2 in the US, both used for moderate-to-severe pain. Oxycodone is somewhat stronger per milligram and is more often sold as a pure opioid (Roxicodone, OxyContin). Hydrocodone is more often combined with paracetamol (Vicodin, Norco). Subjectively many users describe oxycodone as more euphoric and hydrocodone as more sedating, though individual response varies.
I take prescription opioids — how do I use them safely?
Take only as prescribed; do not crush or chew extended-release tablets (defeats the time-release coating and can produce overdose-level peaks); never combine with benzos or alcohol; store securely (single-tablet doses can kill toddlers); dispose of unused tablets via pharmacy take-back; and carry naloxone. Tell your prescriber if you find yourself running out before refill dates — that's an early warning sign of escalation.