Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Hydrochlorothiazide (HCTZ) is a thiazide diuretic: it blocks salt reabsorption in the kidney, so more salt and water leave the body, and over time it relaxes blood vessels. It is one of the most widely used medicines for high blood pressure, often combined with other blood pressure medicines, and is also used for fluid retention. It is sold as Microzide, among other names.
Hydrochlorothiazide is cleared unchanged by the kidneys, so liver-enzyme genes play no part. Studies have looked for genes linked to how much blood pressure falls, such as ADD1 (alpha-adducin, variant rs4961) and NEDD4L, which affect how the kidney handles salt, and to side effects such as low potassium and raised blood sugar. The findings come from single or a few studies, and there is no CPIC or DPWG guideline.
Every published finding on gene variants and Hydrochlorothiazide. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
ADD1 rs4961: Level 2B · replicated. Efficacy: Essential hypertension, Hypertension. 8.
NEDD4L rs4149601: Level 3. Efficacy: Hypertension. 3.
YEATS4 rs7297610: Level 3. Efficacy: Essential hypertension, Hypertension. 2.
NEDD4L rs4149601: Level 3. Efficacy: Hypertension. 2.
Studies of how quickly the body processes this medication.
Studies of how well it worked in people carrying a variant.
Studies of how much of the drug people needed or tolerated.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Thalitone (Thiazide Diuretics)
Thiazide Diuretics (class) (Thiazide Diuretics)
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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