Losartan/Hydrochlorothiazide

Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026

Losartan/hydrochlorothiazide is a fixed-dose combination antihypertensive that pairs the angiotensin II receptor blocker (ARB) losartan with the thiazide diuretic hydrochlorothiazide. It is used to treat hypertension in patients who are not adequately controlled on either agent alone, or as initial therapy when blood pressure goals warrant two complementary mechanisms. The two components act on different pathways, and losartan partially offsets the potassium loss caused by hydrochlorothiazide.

Read the sources → Compare profiles

Publication status

Exploratory record, not a reviewed medical publication.

See the editorial and medical-review policies for the publication gate.

This generated database record has not completed a claim-level review by a qualified human medical reviewer. Bibliography links and evidence labels are not approval. The page remains available for reference and is excluded from search indexing.

In short

What the research says.

A quick, data-only summary. The full evidence, dosing, and sources are below.

Losartan/hydrochlorothiazide is a fixed-dose combination antihypertensive that pairs the angiotensin II receptor blocker (ARB) losartan with the thiazide diuretic hydrochlorothiazide. NutriStack rates the supporting evidence as strong. Common adult dosing is Available as losartan/HCTZ 50/12.5 mg, 100/12.5 mg, and 100/25 mg tablets. Typical adult dosing is one tablet once daily; therapy is usually individualized by first titrating the components, with a usual maximum of losartan 100 mg plus hydrochlorothiazide 25 mg per day. Not recommended as initial therapy in patients with hepatic impairment or in volume-depleted patients., though a prescriber sets the actual dose. With long-term use it can deplete potassium, magnesium, zinc. This profile indexes 3 sources.

What it's good for

Treatment of hypertension (high blood pressure)^1,3
Blood pressure control when monotherapy is insufficient^3,1
Reduction of cardiovascular and stroke risk associated with lowering elevated blood pressure¹

What to watch for

Dizziness or lightheadedness, especially on standing (orthostatic hypotension)
Hypotension, particularly in volume- or salt-depleted patients
Hypokalemia (low potassium) from the thiazide component
Pregnancy (drugs acting on the renin-angiotensin system can cause fetal injury and death; discontinue when pregnancy is detected)^2,3
Known hypersensitivity to losartan, hydrochlorothiazide, or other sulfonamide-derived drugs^3,1

The bottom line

Evidence rating strong. Most-documented uses: treatment of hypertension (high blood pressure), blood pressure control when monotherapy is insufficient, reduction of cardiovascular and stroke risk associated with lowering elevated blood pressure. 3 sources indexed (2002–2019), with 0 interaction records on file.

The science

How it works, mechanistically.

Core mechanism

Losartan selectively blocks the binding of angiotensin II to the angiotensin II type 1 (AT1) receptor, preventing angiotensin II-mediated vasoconstriction and reducing aldosterone secretion, which lowers blood pressure and tends to conserve potassium. Hydrochlorothiazide inhibits the sodium-chloride cotransporter in the distal convoluted tubule of the nephron, increasing urinary excretion of sodium and water and producing a diuretic and antihypertensive effect; over time it also reduces peripheral vascular resistance. Hydrochlorothiazide increases distal sodium delivery and aldosterone activity, promoting urinary potassium and magnesium loss, while losartan's suppression of aldosterone tends to blunt the thiazide-induced kaliuresis, so the combination produces a smaller net change in serum potassium than either drug would alone.^1,2

Class

Angiotensin II receptor blocker plus thiazide diuretic (fixed-dose combination)

Dosing

Dosing & protocol.

Common range

Available as losartan/HCTZ 50/12.5 mg, 100/12.5 mg, and 100/25 mg tablets. Typical adult dosing is one tablet once daily; therapy is usually individualized by first titrating the components, with a usual maximum of losartan 100 mg plus hydrochlorothiazide 25 mg per day. Not recommended as initial therapy in patients with hepatic impairment or in volume-depleted patients.

Recommended form

Oral tablet, taken once daily

Can be taken with or without food. Food does not meaningfully affect the antihypertensive effect of either component. Taking the dose in the morning is often preferred to limit nocturnal diuresis. Losartan is converted to an active carboxylic acid metabolite (E-3174) that contributes most of the AT1 receptor blockade.^2,3

Depletions

What it depletes.

Nutrients this medication can lower over time, and what to replace.

Potassium

Moderate

Hydrochlorothiazide increases urinary potassium loss, although losartan may offset or reverse this in some patients.

Replace Potassium only if prescribedMonitor Serum potassiumOnset Days to weeks after initiation or dose increase

Magnesium

Moderate

Thiazide diuretics can increase urinary magnesium loss.

Replace Magnesium GlycinateMonitor Serum magnesiumOnset Weeks to months

Zinc

Mild

Thiazide diuretics increase urinary zinc excretion through enhanced distal tubular fluid flow and reduced zinc reabsorption, which can lower body zinc stores over long-term use.

Replace Zinc gluconateMonitor Plasma zincOnset Months of chronic therapy

Sodium

Mild

As a natriuretic agent, hydrochlorothiazide directly increases renal sodium excretion; combined with reduced thirst or low sodium intake in older adults this can produce hyponatremia. This is an intended pharmacologic effect rather than a nutritional deficiency, but symptomatic hyponatremia is a recognized adverse outcome.

Monitor Serum sodiumOnset Days to weeks after initiation

Full Losartan/Hydrochlorothiazide depletion and interaction guide →

Safety

Full safety detail.

Side effects

Dizziness or lightheadedness, especially on standing (orthostatic hypotension)
Hypotension, particularly in volume- or salt-depleted patients
Hypokalemia (low potassium) from the thiazide component
Hyperkalemia (high potassium), more likely with renal impairment, potassium supplements, or potassium-sparing agents
Hyponatremia and hypomagnesemia
Increased uric acid with possible gout flares
Increased blood glucose and altered lipid levels
Increased serum creatinine or worsening renal function
Photosensitivity skin reactions
Fatigue, headache, and upper respiratory symptoms

Contraindications

Pregnancy (drugs acting on the renin-angiotensin system can cause fetal injury and death; discontinue when pregnancy is detected)^2,3
Known hypersensitivity to losartan, hydrochlorothiazide, or other sulfonamide-derived drugs^3,1
Anuria
Concomitant use with aliskiren in patients with diabetes mellitus
Severe renal impairment (reduced thiazide efficacy and risk of azotemia) and severe hepatic impairment²
Caution with concurrent potassium supplements, potassium-sparing diuretics, or potassium-containing salt substitutes due to hyperkalemia risk^2,3

Sources

Sources, by evidence tier.

Numbered references. Citations throughout the page link here.

Randomized controlled trials

1Cardiovascular morbidity and mortality in the Losartan Intervention For Endpoint reduction in hypertension study (LIFE): a randomised trial against atenololPMIDDahlof B, Devereux RB, Kjeldsen SE, et al. · The Lancet · 2002
Losartan-based therapy reduced the composite of cardiovascular death, stroke, and myocardial infarction, driven mainly by a significant reduction in stroke, compared with atenolol-based therapy at similar blood pressure reductions.

Reviews & position papers

2Hydrochlorothiazide: pharmacology, clinical use, and electrolyte effects (review of thiazide diuretic therapy)Sica DA · Journal of Clinical Hypertension · 2004
Hydrochlorothiazide increases distal sodium delivery and promotes kaliuresis and magnesium wasting; combining it with a renin-angiotensin system blocker mitigates but does not eliminate hypokalemia risk.

Reference material

3Hyzaar (losartan potassium and hydrochlorothiazide) US Prescribing InformationMerck Sharp & Dohme Corp. · FDA-approved product label · 2019
Fixed-dose losartan/HCTZ lowers blood pressure additively; losartan attenuates the hypokalemic effect of hydrochlorothiazide, and the combination is contraindicated in pregnancy.

FAQ

Common questions.

Quick answers about Losartan/Hydrochlorothiazide, drawn from the data on this page.

What is Losartan/Hydrochlorothiazide?

Losartan/hydrochlorothiazide is a fixed-dose combination antihypertensive that pairs the angiotensin II receptor blocker (ARB) losartan with the thiazide diuretic hydrochlorothiazide. It is used to treat hypertension in patients who are not adequately controlled on either agent alone, or as initial therapy when blood pressure goals warrant two complementary mechanisms. The two components act on different pathways, and losartan partially offsets the potassium loss caused by hydrochlorothiazide.

What is Losartan/Hydrochlorothiazide used for?

Commonly cited benefits of Losartan/Hydrochlorothiazide include: Treatment of hypertension (high blood pressure); Blood pressure control when monotherapy is insufficient; Reduction of cardiovascular and stroke risk associated with lowering elevated blood pressure. NutriStack rates the overall evidence as strong.

What is a typical dose of Losartan/Hydrochlorothiazide?

A typical adult dose of Losartan/Hydrochlorothiazide is Available as losartan/HCTZ 50/12.5 mg, 100/12.5 mg, and 100/25 mg tablets. Typical adult dosing is one tablet once daily; therapy is usually individualized by first titrating the components, with a usual maximum of losartan 100 mg plus hydrochlorothiazide 25 mg per day. Not recommended as initial therapy in patients with hepatic impairment or in volume-depleted patients.. The commonly recommended form is Oral tablet, taken once daily. These are general ranges, not personalized advice; confirm the right dose with a clinician.

What are the side effects of Losartan/Hydrochlorothiazide?

Reported side effects include dizziness or lightheadedness, especially on standing (orthostatic hypotension), hypotension, particularly in volume- or salt-depleted patients, hypokalemia (low potassium) from the thiazide component, hyperkalemia (high potassium), more likely with renal impairment, potassium supplements, or potassium-sparing agents, hyponatremia and hypomagnesemia, increased uric acid with possible gout flares. This is educational information; check with a healthcare professional before use.

How strong is the evidence for Losartan/Hydrochlorothiazide?

NutriStack rates this as Strong, meaning multiple high-quality meta-analyses or systematic reviews converge on the same finding. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.

Use this with your stack

Losartan/Hydrochlorothiazide in NutriStack.

Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.

Download on the App Store → Read the methodology