Metformin and Verapamil: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Verapamil
Metformin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced glucose-lowering effect of metFORMIN, an increased risk of hyperglycemia and potential loss of glycemic control
Interaction Deep Dive
In healthy patients undergoing oral glucose tolerance testing (N=12), coadministration of verapamil with metFORMIN led to a 62.5% decrease in metFORMIN's ability to reduce maximum glucose concentrations, as well as a 238% decrease in metFORMIN's ability to reduce the glucose AUC.2. Calcium channel blockers such as verapamil may tend to produce hyperglycemia and may lead to loss of glycemic control. Observe the patients for loss of blood glucose control when such drugs are administered to a patient receiving metFORMIN. When such drugs are withdrawn from a patient receiving metFORMIN, the patient should be observed closely for hypoglycemia 1.
Why it happens (mechanism)
Inhibition of organic cation transporter 1 (OCT1)-mediated metFORMIN transport by verapamil
Literature reports
1 report — tap to read
a) In healthy patients undergoing oral glucose tolerance testing (N=12), coadministration of verapamil with metFORMIN led to a 62.5% decrease in metFORMIN's ability to reduce maximum glucose concentrations, as well as a 238% decrease in metFORMIN's ability to reduce the glucose AUC. MetFORMIN alone decreased mean maximum glucose concentration by 16 mg/dL, and this was reduced to 6 mg/dL with verapamil coadministration. Mean glucose AUC(0 to 60 minutes) decreased by 594 mg x dL/min with metFORMIN alone, while it increased by 6 mg x dL/min with verapamil coadministration. Mean glucose total AUC decreased by 509 mg x dL/min with metFORMIN alone, and increased by 702 mg x dL/min with verapamil coadministration 2.
Common questions
Can I take Metformin and Verapamil together?
Reduced glucose-lowering effect of metFORMIN, an increased risk of hyperglycemia and potential loss of glycemic control Always confirm with your pharmacist or prescriber before making any change.
How serious is the Metformin and Verapamil interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Metformin or Verapamil need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: KAZANO oral tablets, alogliptin, metformin hydrochloride oral tablets. Takeda Pharmaceuticals America Inc (per FDA), Lexington, MA, 2023. DailyMed
- Cho SK, Kim CO, Park ES, et al: Verapamil decreases the glucose-lowering effect of metformin in healthy volunteers. Br J Clin Pharmacol 2014; 78(6):1426-1432. PubMed
Keep reading about Verapamil
Keep reading about Metformin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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