While asked by my mom to help find something for her in the dresser, I discovered a small bottle of pills that was from the year 1988, a few years before I was born. They were actually my dad's, as the bottle had his name on it.
Pentazocine
Well-documented
Well-documented
Multiple authoritative sources agree on dosing and effects.
- 2 corroborating sources
- 2 ROAs with full dose ladders
- duration data present
- 29 combo interactions documented
- PubChem toxicity data
Well-documented
Multiple authoritative sources agree on dosing and effects.
- 2 corroborating sources
- 2 ROAs with full dose ladders
- duration data present
- 29 combo interactions documented
- PubChem toxicity data
Aliases: Talwin
Summary
A synthetic opioid used as an analgesic. It is only used IM and IV in the medical field and has respiratory depressant effects. It is pregnancy category C and schedule IV in the US.
Dose Information
| ROA | Light | Common | Strong | Heavy |
|---|---|---|---|---|
| Intramuscular | 10-20mg | 20mg-30mg | 30-60mg | 60mg+ |
| Intravenous | 5-10mg | 10-20mg | 30mg+ | - |
Onset, Duration & After-effects
| ROA | Onset | Peak |
|---|---|---|
| Intramuscular | 15-20 min | 2-3 hrs |
| Intravenous | 2-3 min | 2-3 hrs |
Opioid MME Calculator
⚠ Citation & Disclaimer:
Conversion factors sourced from the
NIH HEAL Initiative MME Calculator (Adams et al., PAIN 2025),
the CDC 2022 Clinical Practice Guideline for Prescribing Opioids for Pain,
and the MDCalc MME Calculator.
These are approximate equianalgesic ratios for educational reference only.
Individual responses vary significantly based on genetics, tolerance, cross-tolerance, and route of administration.
This is not medical advice. Do not use these conversions to adjust opioid dosing without professional medical guidance.
mg
27
mg
Pentazocine
≈
—
mg
Morphine
| Substance | Equivalent Dose | MME Factor |
|---|
⚠ Equianalgesic dose ratios are approximations and do not account for genetic factors, tolerance, incomplete cross-tolerance, or pharmacokinetic variations. Methadone conversion is especially variable at higher doses. Always consult a healthcare provider before making any changes to opioid therapy.
Tolerance
Build-up
develops within days of regular use; analgesic tolerance faster than respiratory depression tolerance
Reset
Falls quickly once you stop, at a rate you can't judge. After any break, treat your tolerance as gone.
No tolerance chart. Our decay curves for opioids were estimates, and a curve can make tolerance look longer-lasting than it is, which is the dangerous direction.
Opioid tolerance drops fast when you stop, and even a few days off can be enough, so a dose that used to be normal can now stop your breathing. Overdose deaths rise sharply after prison, detox or leaving treatment, and tolerance also falls during a hospital stay. After any break, start with a much smaller amount, try a test dose first, don't use alone, and keep naloxone within reach. Alcohol, benzodiazepines, gabapentinoids and other sedatives make an opioid overdose much more likely.
Sources: FRANK: heroin · National Harm Reduction Coalition · WHO: opioid overdose · Merrall et al. 2010 · Binswanger et al. 2007 · Strang et al. 2003 · FDA 2019: gabapentinoids and breathing
Combinations
Cross-Check Pentazocine with another substanceCommunity Trip Reports
Anecdotal first-person accounts from Reddit, Erowid, Bluelight, and Dose.wiki. Click a source to expand. Reports are harm-reduction context, not medical guidance. Tags summarise each author's own verdict — how reports are classified.
Erowid 2 reports 2 neutral visit
In 2004 I was living abroad under sunny skies to pursue my narcotics vocation. Having moved to a new area to detox a huge heroin habit, I knew nobody to score from when impelled to relapse. Hoping to obtain under-the-counter buprenorphine, I was instead offered pentazocine in 2 ml ampoule form.
Pentazocine's nerd page
Pharmacology, chemical data, effect profiles, and more
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Helpful Links
Add to PsychonautWiki Journal
The PsychonautWiki Journal logging app doesn't include every substance. To track Pentazocine there, start adding an ingestion, search for the name, and choose to add it as a custom substance. Paste these values:
⬇ Download import file
Import this file as custom substances
and you get "Pentazocine (Substance Search)" with every
route's full dose ladder and timeline, no typing. Works on iOS and
Android (v15+); the format is confirmed by the app's
developer. The manual values below work for older
versions.
Name
Pentazocine
Unit
mg
Description
Pentazocine Source: SubstanceSearch (substancesearch.com) Intramuscular dose (mg): light 10-20 · common 20-30 · strong 30-60 · heavy 60+ Intravenous dose (mg): light 5-10 · common 10-20 · strong 30+ Intramuscular duration: onset 15-20m · peak 2-3h · after-effects 1-12h Intravenous duration: onset 2-3m · peak 2-3h · after-effects 1-12h Note: ranges are harm-reduction guidance, not a prescription. Start low, go slow, and test your substances.
Tip: for quicker logging you can also add a Custom Unit in the app, e.g. common dose ~ 25 mg (Intramuscular).
The app keeps custom substances simple, so the full dose ranges live in the description text above. Ranges are harm-reduction guidance, not a prescription.
Report an issue or suggest an edit
Spotted incorrect or dangerous information, have a correction, a new study, or a useful addition for Pentazocine? Let us know. Reports are reviewed by moderators — this is not posted publicly.