Drug interactions
Hydrochlorothiazide + Metformin
Severity: Moderate
Hydrochlorothiazide and Metformin: 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
Thiazides can raise blood glucose and weaken the glycemic control achieved with metformin. Thiazide-related reduction in renal function could also raise metformin exposure, which matters because of lactic acidosis risk.
What this interaction means in plain words
Hydrochlorothiazide and Metformin 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.
Hydrochlorothiazide belongs to Cardiovascular; Metformin belongs to Endocrine.
Why it happens
Thiazides impair glucose tolerance through hypokalemia and reduced insulin secretion, and may reduce renal function or compete for renal tubular secretion of metformin.
What to do
Monitor blood glucose and HbA1c, and renal function (eGFR) periodically. Adjust antidiabetic therapy if control worsens and reduce or stop metformin if renal function declines significantly.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Hydrochlorothiazide and Metformin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Hydrochlorothiazide
Other interactions of Metformin
Frequently asked questions
Can I take Hydrochlorothiazide with Metformin?
MediHelp rates the interaction as moderate. Hydrochlorothiazide and Metformin 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. Thiazides can raise blood glucose and weaken the glycemic control achieved with metformin. Thiazide-related reduction in renal function could also raise metformin exposure, which matters because of lactic acidosis risk.
How serious is the interaction between Hydrochlorothiazide and Metformin?
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, and renal function (eGFR) periodically. Adjust antidiabetic therapy if control worsens and reduce or stop metformin if renal function declines significantly.
What other medicines interact with Hydrochlorothiazide?
MediHelp also lists interactions of Hydrochlorothiazide with, for example, Dofetilide, Amifostine, Amiodarone. The full list is on the Hydrochlorothiazide page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
