Does Metolazone Interact with Methenamine Salts?
Metolazone and Methenamine Salts have a moderate drug interaction according to U.S. FDA drug labeling data. Efficacy may be decreased due to urinary alkalizing effect of metolazone. The mechanism involves urinary alkalizing effect reduces methenamine efficacy. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Moderate
- Metolazone Class
- Thiazide-like Diuretic
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Metolazone and Methenamine Salts occurs because urinary alkalizing effect reduces methenamine efficacy. Clinically, this means efficacy may be decreased due to urinary alkalizing effect of metolazone. This is classified as a moderate interaction. While it may not require stopping either medication, your healthcare provider should be aware you are taking both so they can monitor for potential effects and adjust treatment if necessary.
What To Tell Your Doctor or Pharmacist
If you are taking Metolazone and your doctor is considering prescribing Methenamine Salts (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider