Drug interactions
Metformin-sitagliptin + Promethazine
Severity: Minor
Metformin-sitagliptin and Promethazine: minor 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
Promethazine, a phenothiazine antihistamine, may cause hyperglycemia and modestly reduce glucose control in diabetic patients. Glycemia may need reassessment when it is started or withdrawn.
What this interaction means in plain words
Metformin-sitagliptin and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Metformin-sitagliptin belongs to Endocrine; Promethazine belongs to Respiratory.
Why it happens
Phenothiazine effects on insulin release and sensitivity may oppose antidiabetic drugs; the mechanism is not firmly established.
What to do
Check blood glucose more often during prolonged promethazine use and adjust the antidiabetic regimen if control worsens.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Metformin-sitagliptin
Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Metformin-sitagliptin with Promethazine?
MediHelp rates the interaction as minor. Metformin-sitagliptin and Promethazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Promethazine, a phenothiazine antihistamine, may cause hyperglycemia and modestly reduce glucose control in diabetic patients. Glycemia may need reassessment when it is started or withdrawn.
How serious is the interaction between Metformin-sitagliptin and Promethazine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check blood glucose more often during prolonged promethazine use and adjust the antidiabetic regimen if control worsens.
What other medicines interact with Metformin-sitagliptin?
MediHelp also lists interactions of Metformin-sitagliptin with, for example, Clozapine, Contrast media, Diatrizoate meglumine / diatrizoate. The full list is on the Metformin-sitagliptin page.
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