Information last reviewed: May 2026 — for educational purposes only.
Losartan, sold under the brand name Cozaar, is an angiotensin II receptor blocker (ARB) that selectively blocks the AT1 receptor to lower blood pressure. It is a prescription medication and one of the most widely used ARBs globally. Unlike ACE inhibitors such as lisinopril, losartan does not cause a dry cough, making it a preferred alternative for patients who develop that class-effect side effect.
Uses of Losartan
Losartan is approved for hypertension in adults and children aged six and older, for reducing the risk of stroke in patients with hypertension and left ventricular hypertrophy, and for slowing the progression of kidney disease in patients with type 2 diabetes and nephropathy (supported by the landmark RENAAL trial). It carries a mild uricosuric effect — a unique property among ARBs that slightly lowers serum uric acid levels, which may offer a modest benefit to hypertensive patients prone to gout. Hyzaar is a fixed-dose combination product containing losartan 50 mg with hydrochlorothiazide 12.5 mg.
Mechanism, Warnings, and Key Interactions
Losartan blocks angiotensin II at the AT1 receptor, preventing vasoconstriction and aldosterone secretion. Its active metabolite EXP3174 is responsible for the majority of AT1 receptor blockade, giving losartan a longer effective duration than its own half-life would suggest. Losartan is absolutely contraindicated in pregnancy — it is classified in pregnancy category D/X and causes fetotoxic effects including oligohydramnios, fetal renal failure, and skull hypoplasia. Hyperkalemia is a significant risk, particularly when combined with potassium-sparing diuretics, ACE inhibitors, aldosterone antagonists, or potassium supplements. Losartan must not be combined with direct renin inhibitor aliskiren in patients with diabetes. Angioedema can occur, although it is considerably rarer than with ACE inhibitors.
Available Strengths and Dosing
Losartan tablets are available in 25 mg, 50 mg, and 100 mg strengths. The standard starting dose for hypertension is 50 mg once daily, which can be increased to 100 mg once daily. The 25 mg starting dose is used in patients with volume depletion or hepatic impairment. Hyzaar combines losartan 50 mg with hydrochlorothiazide 12.5 mg in a single tablet for patients requiring combination therapy.
Pricing Overview
Generic losartan is available at low cost from most major pharmacies, often under $15–$20 per month for the 50 mg dose. The branded Cozaar is more expensive. Hyzaar combination tablets are also available in generic form at competitive prices. Contact Lucas Clinic for current pricing and access details.
Frequently Asked Questions
Why is losartan preferred over ACE inhibitors for some patients?
The primary reason is the absence of dry cough. ACE inhibitors cause a persistent, bothersome dry cough in 10–20% of patients due to bradykinin accumulation — losartan and other ARBs do not share this mechanism and therefore do not cause this side effect. Patients who develop ACE inhibitor cough are commonly switched to losartan or another ARB without losing antihypertensive or renoprotective efficacy.
Is losartan safe to take during pregnancy?
No. Losartan is contraindicated throughout pregnancy due to serious fetotoxic effects. When the renin-angiotensin system is suppressed during the second and third trimesters, fetal renal development is severely affected, potentially causing oligohydramnios, fetal renal failure, skeletal abnormalities including skull hypoplasia, and fetal death. Women of childbearing potential should use effective contraception and discontinue losartan immediately upon confirmed or suspected pregnancy.
What makes losartan unique among ARBs regarding uric acid?
Losartan has a mild uricosuric effect — it increases renal excretion of uric acid, modestly lowering serum uric acid levels. This property is not shared by other ARBs and may be clinically useful in hypertensive patients who also have hyperuricemia or are prone to gout attacks. While not a substitute for dedicated urate-lowering therapy, it is a meaningful distinguishing feature when selecting among ARBs.
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