Drug interactions
Clarithromycin + Thioridazine
Severity: Contraindicated
Clarithromycin 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
Both drugs prolong the QT interval, and thioridazine is associated with torsades de pointes and sudden death. Clarithromycin may also inhibit thioridazine metabolism, raising its levels.
What this interaction means in plain words
Clarithromycin 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.
Clarithromycin belongs to Anti Bacterial; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with CYP3A4 and CYP2D6-related metabolic inhibition raising thioridazine exposure.
What to do
Do not coadminister; use a non-macrolide or non-QT-prolonging antibiotic.
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 Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine 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 Clarithromycin with Thioridazine?
MediHelp rates the interaction as contraindicated. Clarithromycin 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. Both drugs prolong the QT interval, and thioridazine is associated with torsades de pointes and sudden death. Clarithromycin may also inhibit thioridazine metabolism, raising its levels.
How serious is the interaction between Clarithromycin 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: Do not coadminister; use a non-macrolide or non-QT-prolonging antibiotic.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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