Drug interactions
Lithium + Thioridazine
Severity: Contraindicated
Lithium and Thioridazine: contraindicated 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 strongly prolongs the QTc interval and can cause torsades de pointes, and lithium can add to QT effects and electrolyte disturbance. Combined use may also raise the risk of neurotoxicity. Thioridazine labeling carries a boxed warning on QT risk and the pair is generally avoided.
What this interaction means in plain words
Lithium and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Lithium belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with possible pharmacodynamic neurotoxic synergy.
What to do
Avoid the combination and use a lower-QT-risk antipsychotic. If lithium must be continued, obtain an ECG, check potassium and magnesium, and monitor for neurotoxicity.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Lithium
- Lithium + Vandetanib Contraindicated
- Aceclofenac + Lithium Major
- Acemetacin + Lithium Major
- Amisulpride + Lithium Major
- Amlodipine-benazepril + Lithium Major
- Amlodipine-hydrochlorothiazide-valsartan + Lithium 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 Lithium with Thioridazine?
MediHelp rates the interaction as contraindicated. Lithium and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Thioridazine strongly prolongs the QTc interval and can cause torsades de pointes, and lithium can add to QT effects and electrolyte disturbance. Combined use may also raise the risk of neurotoxicity. Thioridazine labeling carries a boxed warning on QT risk and the pair is generally avoided.
How serious is the interaction between Lithium and Thioridazine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and use a lower-QT-risk antipsychotic. If lithium must be continued, obtain an ECG, check potassium and magnesium, and monitor for neurotoxicity.
What other medicines interact with Lithium?
MediHelp also lists interactions of Lithium with, for example, Vandetanib, Aceclofenac, Acemetacin. The full list is on the Lithium page.
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