Last reviewed 2026-04-23 · How we verify

losartan + hydrochlorothiazide, if necessary

Losartan is an angiotensin II receptor antagonist that blocks the action of angiotensin II, a potent vasoconstrictor, to relax blood vessels and lower blood pressure. Hydrochlorothiazide is a thiazide diuretic that increases urine production to reduce blood pressure.

Losartan is an angiotensin II receptor antagonist that blocks the action of angiotensin II, a potent vasoconstrictor, to relax blood vessels and lower blood pressure. Hydrochlorothiazide is a thiazide diuretic that increases urine production to reduce blood pressure. Used for Hypertension, Chronic kidney disease.

At a glance

Mechanism of action

Losartan works by blocking the angiotensin II receptor, which is part of the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure. By blocking this receptor, losartan prevents the vasoconstriction and fluid retention caused by angiotensin II, leading to a decrease in blood pressure. Hydrochlorothiazide, on the other hand, increases urine production by inhibiting the sodium-chloride cotransporter in the distal convoluted tubule, which leads to a decrease in fluid volume and a subsequent decrease in blood pressure.

Approved indications

• Hypertension
• Chronic kidney disease

Common side effects

• Dizziness
• Headache
• Fatigue
• Cough
• Diarrhea

Key clinical trials

• A 52 Week Study to Evaluate the Effects of Losartan With or Without HCTZ on Plasma Glucose, Metabolic Parameters, Blood Pressure in Hypertensive Patients With Metabolic Syndrome (0954A-331) (PHASE3)
• Randomized Controlled Trial of Renal Denervation for Resistant Hypertension (PHASE3)
• Olmesartan Medoxomil Versus Losartan in Elderly and Very Elderly (PHASE3)

Primary sources

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