Drug interactions
Codeine + Thioridazine
Severity: Moderate
Codeine and Thioridazine: moderate 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 codeine's sedative and respiratory depressant effects and inhibits CYP2D6, which can reduce conversion of codeine to morphine and blunt analgesia. Thioridazine also prolongs the QT interval, adding to the overall risk in affected patients.
What this interaction means in plain words
Codeine and Thioridazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Codeine belongs to Musculoskeletal; Thioridazine belongs to Central Nervous System.
Why it happens
Additive CNS depression plus CYP2D6 inhibition by thioridazine reducing codeine activation.
What to do
Monitor sedation, respiratory status and pain control; consider a non-CYP2D6-dependent opioid if analgesia is inadequate. Check ECG and electrolytes if QT risk factors exist.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Codeine
- Alvimopan + Codeine Contraindicated
- Codeine + Isocarboxazid Contraindicated
- Codeine + Olanzapine / samidorphan Contraindicated
- Codeine + Phenelzine Contraindicated
- Codeine + Tranylcypromine Contraindicated
- Alfentanil + Codeine Major
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 Codeine with Thioridazine?
MediHelp rates the interaction as moderate. Codeine and Thioridazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Thioridazine adds to codeine's sedative and respiratory depressant effects and inhibits CYP2D6, which can reduce conversion of codeine to morphine and blunt analgesia. Thioridazine also prolongs the QT interval, adding to the overall risk in affected patients.
How serious is the interaction between Codeine and Thioridazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor sedation, respiratory status and pain control; consider a non-CYP2D6-dependent opioid if analgesia is inadequate. Check ECG and electrolytes if QT risk factors exist.
What other medicines interact with Codeine?
MediHelp also lists interactions of Codeine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Codeine page.
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