Drug interactions
Fentanyl transdermal + Thioridazine
Severity: Major
Fentanyl transdermal and Thioridazine: 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
Combining a transdermal opioid with a sedating phenothiazine can cause additive CNS and respiratory depression, hypotension, profound sedation and coma. The prolonged action of the patch makes the effect slow to reverse.
What this interaction means in plain words
Fentanyl transdermal and Thioridazine 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 pharmacodynamic CNS and respiratory depression from opioid agonism plus antipsychotic sedative and alpha-blocking effects.
What to do
Use only when alternatives are inadequate, with the lowest effective doses and careful titration. Monitor sedation, respiratory rate and blood pressure, particularly after 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?
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Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Fentanyl transdermal with Thioridazine?
MediHelp rates the interaction as major. Fentanyl transdermal and Thioridazine 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. Combining a transdermal opioid with a sedating phenothiazine can cause additive CNS and respiratory depression, hypotension, profound sedation and coma. The prolonged action of the patch makes the effect slow to reverse.
How serious is the interaction between Fentanyl transdermal and Thioridazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use only when alternatives are inadequate, with the lowest effective doses and careful titration. Monitor sedation, respiratory rate and blood pressure, particularly after dose changes.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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