Naltrexone and Thioridazine Interaction
Drug interaction information between Naltrexone and Thioridazine.
Naltrexone and Thioridazine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Naltrexone and Thioridazine. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Taking these two drugs together can cause an additive effect that makes you feel very sleepy and tired. Both medications impact the brain in a way that increases drowsiness.
What To Do
Tell your doctor if you feel unusually sleepy or sluggish. They may need to monitor your symptoms or adjust your medications.
FDA Label Information
Lethargy and somnolence have been reported following doses of naltrexone hydrochloride and thioridazine.
Naltrexone Also Interacts With
- Disulfiram minor
- Acamprosate minor
- Glecaprevir/Pibrentasvir minor
- Nabilone minor
Thioridazine Also Interacts With
- Fluoxetine major
- Paroxetine major
- Rolapitant major
- Abiraterone moderate
- Darifenacin moderate
Frequently Asked Questions
Can I take Naltrexone and Thioridazine together?
This is a minor interaction. Tell your doctor if you feel unusually sleepy or sluggish. They may need to monitor your symptoms or adjust your medications.
How serious is the interaction between Naltrexone and Thioridazine?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Naltrexone and Thioridazine interact?
Taking these two drugs together can cause an additive effect that makes you feel very sleepy and tired. Both medications impact the brain in a way that increases drowsiness.
Understanding the Naltrexone and Thioridazine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Naltrexone belongs to the Opioid Antagonist class and Thioridazine belongs to the Typical Antipsychotic (Phenothiazine) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Taking these two drugs together can cause an additive effect that makes you feel very sleepy and tired. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Naltrexone has 5 total documented interactions on file in this dataset, and Thioridazine has 17. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Tell your doctor if you feel unusually sleepy or sluggish. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Naltrexone or Thioridazine based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.