Drug interactions
Fentanyl transdermal + Promethazine
Severity: Major
Fentanyl transdermal 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
Promethazine is a sedating phenothiazine antihistamine, and fentanyl is a potent opioid. Used together they increase the risk of profound sedation, respiratory depression, hypotension and coma. This is a labeled concern for opioids combined with other CNS depressants.
What this interaction means in plain words
Fentanyl transdermal 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.
Why it happens
Additive central nervous system and respiratory depression through opioid receptor agonism and H1 antagonism with sedative phenothiazine effects.
What to do
Reserve the combination for patients without adequate alternatives, using the lowest effective doses and shortest duration. Monitor for sedation and respiratory depression, particularly at initiation and dose changes.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fentanyl transdermal and Promethazine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Fentanyl transdermal with Promethazine?
MediHelp rates the interaction as major. Fentanyl transdermal 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. Promethazine is a sedating phenothiazine antihistamine, and fentanyl is a potent opioid. Used together they increase the risk of profound sedation, respiratory depression, hypotension and coma. This is a labeled concern for opioids combined with other CNS depressants.
How serious is the interaction between Fentanyl transdermal 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: Reserve the combination for patients without adequate alternatives, using the lowest effective doses and shortest duration. Monitor for sedation and respiratory depression, particularly at initiation and dose changes.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
