Drug interactions
Meperidine + Thioridazine
Severity: Major
Meperidine 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
Thioridazine adds to meperidine's sedation, hypotension and respiratory depression. Thioridazine also prolongs the QT interval and has strong anticholinergic activity, and phenothiazines can potentiate opioid effects and increase the risk of serotonin or neuroleptic syndromes.
What this interaction means in plain words
Meperidine 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.
Meperidine belongs to Musculoskeletal; Thioridazine belongs to Central Nervous System.
Why it happens
Additive CNS depression and anticholinergic effects, with possible serotonergic and dopamine-blocking synergy; thioridazine independently prolongs QT.
What to do
Use the lowest doses, monitor sedation, respiration, blood pressure and ECG, and consider an alternative analgesic or antipsychotic.
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 Meperidine
- Alvimopan + Meperidine Contraindicated
- Isocarboxazid + Meperidine Contraindicated
- Meperidine + Methylene blue Contraindicated
- Meperidine + Olanzapine / samidorphan Contraindicated
- Meperidine + Phenelzine Contraindicated
- Meperidine + Procarbazine Contraindicated
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 Meperidine with Thioridazine?
MediHelp rates the interaction as major. Meperidine 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. Thioridazine adds to meperidine's sedation, hypotension and respiratory depression. Thioridazine also prolongs the QT interval and has strong anticholinergic activity, and phenothiazines can potentiate opioid effects and increase the risk of serotonin or neuroleptic syndromes.
How serious is the interaction between Meperidine 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 the lowest doses, monitor sedation, respiration, blood pressure and ECG, and consider an alternative analgesic or antipsychotic.
What other medicines interact with Meperidine?
MediHelp also lists interactions of Meperidine with, for example, Alvimopan, Isocarboxazid, Methylene blue. The full list is on the Meperidine page.
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