Drug interactions
Metformin + Thioridazine
Severity: Moderate
Metformin 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
Phenothiazines can raise blood glucose and impair glycemic control, which may offset the effect of metformin. Glucose may rise while both drugs are given and may fall again if the phenothiazine is stopped.
What this interaction means in plain words
Metformin 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.
Metformin belongs to Endocrine; Thioridazine belongs to Central Nervous System.
Why it happens
Pharmacodynamic antagonism, as phenothiazines can cause hyperglycemia and reduce insulin sensitivity.
What to do
Monitor blood glucose and HbA1c when thioridazine is started, changed or stopped, and adjust the metformin dose if needed.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Metformin
Frequently asked questions
Can I take Metformin with Thioridazine?
MediHelp rates the interaction as moderate. Metformin 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. Phenothiazines can raise blood glucose and impair glycemic control, which may offset the effect of metformin. Glucose may rise while both drugs are given and may fall again if the phenothiazine is stopped.
How serious is the interaction between Metformin 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 blood glucose and HbA1c when thioridazine is started, changed or stopped, and adjust the metformin dose if needed.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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