Losartan and Hydrochlorothiazide Interaction
Drug interaction information between Losartan and Hydrochlorothiazide.
Losartan and Hydrochlorothiazide have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Losartan and Hydrochlorothiazide. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Combining these types of blood pressure medicines can increase the risk of kidney damage and high potassium levels.
What To Do
Your doctor should monitor your kidney function and potassium levels closely if these drugs are used together.
FDA Label Information
The VA NEPHRON trial enrolled 1448 patients with type 2 diabetes, elevated urinary-albumin-to-creatinine ratio, and decreased estimated glomerular filtration rate (GFR 30 to 89.9 ml/min), randomized them to lisinopril or placebo on a background of losartan therapy and followed them for a median of 2.2 years. Patients receiving the combination of losartan and lisinopril did not obtain any additional benefit compared to monotherapy for the combined endpoint of decline in GFR, end state renal disease, or death, but experienced an increased incidence of hyperkalemia and acute kidney injury...
Losartan Also Interacts With
- Aliskiren major
- Lithium moderate
- Fluconazole minor
- Glecaprevir/Pibrentasvir minor
- Hydrochlorothiazide/Lisinopril minor
Hydrochlorothiazide Also Interacts With
- Aliskiren major
- Hydrochlorothiazide/Triamterene major
- Lisinopril major
- Olmesartan moderate
- Spironolactone minor
Frequently Asked Questions
Can I take Losartan and Hydrochlorothiazide together?
This is a minor interaction. Your doctor should monitor your kidney function and potassium levels closely if these drugs are used together.
How serious is the interaction between Losartan and Hydrochlorothiazide?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Losartan and Hydrochlorothiazide interact?
Combining these types of blood pressure medicines can increase the risk of kidney damage and high potassium levels.
Understanding the Losartan and Hydrochlorothiazide Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Losartan belongs to the Angiotensin II Receptor Blocker (ARB) class and Hydrochlorothiazide belongs to the Thiazide Diuretic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Combining these types of blood pressure medicines can increase the risk of kidney damage and high potassium levels. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Losartan has 10 total documented interactions on file in this dataset, and Hydrochlorothiazide has 31. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Your doctor should monitor your kidney function and potassium levels closely if these drugs are used together. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Losartan or Hydrochlorothiazide based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.