Drug interactions
Morphine + Thioridazine
Severity: Moderate
Morphine 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 the sedation and hypotension caused by morphine. Thioridazine also strongly inhibits CYP2D6, but this has limited effect on morphine, which is cleared mainly by glucuronidation. Thioridazine's QT-prolonging effect is an independent concern in the same patient.
What this interaction means in plain words
Morphine 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.
Morphine belongs to Musculoskeletal; Thioridazine belongs to Central Nervous System.
Why it happens
Additive CNS depression and alpha-adrenergic blockade; CYP2D6 inhibition is of minor relevance for morphine.
What to do
Use lower starting doses and titrate slowly while monitoring sedation, blood pressure and respiration. Check ECG and electrolytes if thioridazine is continued.
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 Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Olanzapine / samidorphan Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine 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 Morphine with Thioridazine?
MediHelp rates the interaction as moderate. Morphine 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 the sedation and hypotension caused by morphine. Thioridazine also strongly inhibits CYP2D6, but this has limited effect on morphine, which is cleared mainly by glucuronidation. Thioridazine's QT-prolonging effect is an independent concern in the same patient.
How serious is the interaction between Morphine 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: Use lower starting doses and titrate slowly while monitoring sedation, blood pressure and respiration. Check ECG and electrolytes if thioridazine is continued.
What other medicines interact with Morphine?
MediHelp also lists interactions of Morphine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Morphine page.
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