Olmesartan and Hydrochlorothiazide Interaction
Drug interaction information between Olmesartan and Hydrochlorothiazide.
Olmesartan and Hydrochlorothiazide have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Olmesartan and Hydrochlorothiazide. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Both drugs work to lower blood pressure, which can increase the risk of your blood pressure dropping too low or your kidney function changing.
FDA Label Information
7 DRUG INTERACTIONS Lithium: Risk of lithium toxicity ( 7.2 ) Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): Reduced diuretic, natriuretic and antihypotensive effects; increased risk of renal toxicity ( 7.3 ) Dual inhibition of the renin-angiotensin system: Increased risk of renal impairment, hypotension, and hyperkalemia ( 7.4 ) Colesevelam hydrochloride: Consider administering olmesartan at least 4 hours before colesevelam hydrochloride dose ( 7.5 ) Antidiabetic drugs: Dosage adjustment may be required ( 7.6 ) Cholestyramine and colestipol: Reduced absorption of thiazides ( 7.6 ) 7.1...
Olmesartan Also Interacts With
- Aliskiren major
- Lithium moderate
- Colesevelam moderate
- Cholestyramine moderate
- Colestipol moderate
Hydrochlorothiazide Also Interacts With
- Aliskiren major
- Hydrochlorothiazide/Triamterene major
- Lisinopril major
- Losartan minor
- Spironolactone minor
Frequently Asked Questions
What SPL severity band is on file for Olmesartan + Hydrochlorothiazide?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Hydrochlorothiazide has 31 labeled pairs on file vs Olmesartan's 7. In the moderate band specifically: Olmesartan has 6 (also Lithium, Colesevelam, Cholestyramine, Colestipol); Hydrochlorothiazide has 1.
What mechanism field is on file for Olmesartan and Hydrochlorothiazide?
Both drugs work to lower blood pressure, which can increase the risk of your blood pressure dropping too low or your kidney function changing.
Hydrochlorothiazide carries more major-labeled pairs than Olmesartan
SPL source-record counts only. This page's band is moderate · classes on file: Olmesartan (Angiotensin II Receptor Blocker (ARB)); Hydrochlorothiazide (Thiazide Diuretic).
Hydrochlorothiazide has 3 major-labeled pairs vs Olmesartan's 1. This page itself is in the moderate band, not the major band.
1 major · 6 moderate · 0 minor · 7 total
- Other moderate peers for Olmesartan
- Lithium
- Colesevelam
- Cholestyramine
- Colestipol
3 major · 1 moderate · 27 minor · 31 total
Hydrochlorothiazide has no other moderate-band peer in this dataset besides Olmesartan.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.