Drug interactions
Pentazocine + Promethazine
Severity: Major
Pentazocine and Promethazine: 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 sedating opioid agonist-antagonist and promethazine adds to its CNS and respiratory depressant effects. Marked drowsiness, hypotension and respiratory depression may occur.
What this interaction means in plain words
Pentazocine and Promethazine 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 belongs to Musculoskeletal; Promethazine belongs to Respiratory.
Why it happens
Additive CNS and respiratory depression.
What to do
Reduce initial doses and monitor sedation and respiratory rate, particularly in elderly patients.
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 Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine 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 Pentazocine with Promethazine?
MediHelp rates the interaction as major. Pentazocine and Promethazine 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 sedating opioid agonist-antagonist and promethazine adds to its CNS and respiratory depressant effects. Marked drowsiness, hypotension and respiratory depression may occur.
How serious is the interaction between Pentazocine and Promethazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce initial doses and monitor sedation and respiratory rate, particularly in elderly patients.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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