Fosinopril and Hydrochlorothiazide Interaction
Drug interaction information between Fosinopril and Hydrochlorothiazide.
Fosinopril and Hydrochlorothiazide have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Fosinopril 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
Studies show that taking these two medications together does not change how much of the medicine is absorbed into your bloodstream.
What To Do
No special changes or precautions are usually needed when taking these two drugs at the same time.
FDA Label Information
In separate single or multiple dose pharmacokinetic interaction studies with chlorthalidone, nifedipine, propranolol, hydrochlorothiazide, cimetidine, metoclopramide, propantheline, digoxin, and warfarin, the bioavailability of fosinoprilat was not altered by coadministration of fosinopril with any one of these drugs.
Fosinopril Also Interacts With
- Aliskiren major
- Lithium moderate
- Aspirin minor
- Propranolol minor
- Warfarin minor
Hydrochlorothiazide Also Interacts With
- Aliskiren major
- Hydrochlorothiazide/Triamterene major
- Lisinopril major
- Olmesartan moderate
- Losartan minor
Frequently Asked Questions
Can I take Fosinopril and Hydrochlorothiazide together?
This is a minor interaction. No special changes or precautions are usually needed when taking these two drugs at the same time.
How serious is the interaction between Fosinopril 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 Fosinopril and Hydrochlorothiazide interact?
Studies show that taking these two medications together does not change how much of the medicine is absorbed into your bloodstream.
Understanding the Fosinopril and Hydrochlorothiazide Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Fosinopril belongs to the ACE Inhibitor class and Hydrochlorothiazide belongs to the Thiazide Diuretic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Studies show that taking these two medications together does not change how much of the medicine is absorbed into your bloodstream. 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. Fosinopril has 12 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: No special changes or precautions are usually needed when taking these two drugs at the same time. 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 Fosinopril 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.