Drug interactions
Fentanyl + Pentazocine
Severity: Major
Fentanyl and Pentazocine: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Pentazocine is a mixed agonist-antagonist that can block fentanyl's effects and precipitate withdrawal in patients who are physically dependent on opioids. It also adds to sedation and may reduce analgesic benefit.
What this interaction means in plain words
Fentanyl and Pentazocine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Fentanyl belongs to Musculoskeletal; Pentazocine belongs to Musculoskeletal.
Why it happens
Partial agonist and antagonist activity at mu receptors competes with fentanyl, with kappa agonism and additive CNS depression.
What to do
Avoid combining mixed agonist-antagonists with full agonists in opioid-dependent patients. If it is unavoidable, monitor for withdrawal, reduced analgesia and respiratory depression.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Other interactions of Pentazocine
- Calcium / magnesium / potassium / sodium oxybates + Pentazocine Contraindicated
- Olanzapine / samidorphan + Pentazocine Contraindicated
- Pentazocine + Phenelzine Contraindicated
- Pentazocine + Tranylcypromine Contraindicated
- Alfentanil + Pentazocine Major
- Alprazolam + Pentazocine Major
Frequently asked questions
Can I take Fentanyl with Pentazocine?
MediHelp rates the interaction as major. Fentanyl and Pentazocine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Pentazocine is a mixed agonist-antagonist that can block fentanyl's effects and precipitate withdrawal in patients who are physically dependent on opioids. It also adds to sedation and may reduce analgesic benefit.
How serious is the interaction between Fentanyl and Pentazocine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining mixed agonist-antagonists with full agonists in opioid-dependent patients. If it is unavoidable, monitor for withdrawal, reduced analgesia and respiratory depression.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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