Drug interactions

Diazepam + Fentanyl transmucosal

Severity: Major

Diazepam and Fentanyl transmucosal: major interaction.

Last updated 29 Oct 2026 Sources: US FDA label

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

Taking a benzodiazepine with an opioid causes additive depression of the central nervous system and breathing. Profound sedation, coma and death can occur.

Diazepam

What this interaction means in plain words

Diazepam and Fentanyl transmucosal 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.

Evidence level: High

Why it happens

Additive CNS and respiratory depression through opioid receptor agonism and GABA-A potentiation.

What to do

Reserve combined use for patients with no adequate alternatives, with minimal doses and duration. Monitor respiratory rate and level of sedation and ensure naloxone is accessible.

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?

Bring a full list of your medicines, including over-the-counter products, supplements and herbal remedies, to every pharmacy visit.

Pro+ members

Unlock the full page

Create an account and start a Pro+ trial to unlock the full management advice for Diazepam and Fentanyl transmucosal, 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

Create free account Sign in

Try Pro+ free for 7 days on the web. No card needed.

References

Diazepam - FDA drug label (DailyMed) - section 7 Drug Interactions (class statement: opioids; "The concomitant use of benzodiazepines and opioids increases the risk of respiratory depression because of actions at different receptor sites in the CNS that c") — DailyMed (FDA label)

Calcium / magnesium / potassium / sodium oxybates + Diazepam Contraindicated
Alfentanil + Diazepam Major
Alprazolam + Diazepam Major
Amobarbital + Diazepam Major
Belladonna and opium + Diazepam Major
Benzhydrocodone / acetaminophen + Diazepam Major

Frequently asked questions

Can I take Diazepam with Fentanyl transmucosal?

MediHelp rates the interaction as major. Diazepam and Fentanyl transmucosal 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. Taking a benzodiazepine with an opioid causes additive depression of the central nervous system and breathing. Profound sedation, coma and death can occur.

How serious is the interaction between Diazepam and Fentanyl transmucosal?

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 combined use for patients with no adequate alternatives, with minimal doses and duration. Monitor respiratory rate and level of sedation and ensure naloxone is accessible.

What other medicines interact with Diazepam?

MediHelp also lists interactions of Diazepam with, for example, Calcium / magnesium / potassium / sodium oxybates, Alfentanil, Alprazolam. The full list is on the Diazepam 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.

Download on theApp Store Get it onGoogle Play

Browse A–Z · Drug interactions