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Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 979480
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Losartan potassium tablets are an angiotensin II receptor blocker (ARB) indicated for: • Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. (1.1) • Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy. There is evidence that this benefit does not apply to Black patients. (1.2) • Treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in patients with type 2 diabetes and a history of hypertension. (1.3) 1.1 Hypertension Losartan potassium tablets are indicated for the treatment of hypertension in adults and pediatric patients 6 years of age and older, to lower blood pressure. Lowering blood pressure lowers the risk of fatal and nonfatal cardiovascular (CV) events, primarily strokes and myocardial infarction. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including losartan. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than 1 drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program's Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC). Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. […]
About this medicine
Losartan potassium is an angiotensin II receptor blocker acting on the AT 1 receptor subtype. Losartan potassium, a non-peptide molecule, is chemically described as 2-butyl-4-chloro-1-[ p -( o -1 H tetrazol-5-ylphenyl)benzyl]imidazole-5-methanol monopotassium salt. Its molecular formula is C 22 H 22 ClKN 6 O, and its structural formula is: Losartan potassium, USP is white to off-white powder with a molecular weight of 461.01. It is freely soluble in water; soluble in isopropyl alcohol; slightly soluble in acetonitrile. Oxidation of the 5-hydroxymethyl group on the imidazole ring results in the active metabolite of losartan. Losartan potassium tablets, USP 25 mg, 50 mg and 100 mg contain potassium in the following amounts: 2.12 mg (0.054 mEq), 4.24 mg (0.108 mEq) and 8.48 mg (0.216 mEq), respectively. Each losartan potassium tablet, USP intended for oral administration contains 25 mg or 50 mg or 100 mg of losartan potassium. In addition, each tablet contains the following inactive ingredients: colloidal silica anhydrous, hydroxypropyl cellulose (low substituted), hypromellose, lactose monohydrate, magnesium stearate, maize starch (corn starch), microcrystalline cellulose, polyethylene glycol, sodium starch glycolate, talc and titanium dioxide. Structural Formula
How it works
12.1 Mechanism of Action Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II)] is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system, and an important component in the pathophysiology of hypertension. It also stimulates aldosterone secretion by the adrenal cortex. Losartan and its principal active metabolite block the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT 1 receptor found in many tissues, (e.g., vascular smooth muscle, adrenal gland). There is also an AT 2 receptor found in many tissues but it is not known to be associated with cardiovascular homeostasis. Neither losartan nor its principal active metabolite exhibits any partial agonist activity at the AT 1 receptor, and both have much greater affinity (about 1000-fold) for the AT 1 receptor than for the AT 2 receptor. In vitro binding studies indicate that losartan is a reversible, competitive inhibitor of the AT 1 receptor. The active metabolite is 10 to 40 times more potent by weight than losartan and appears to be a reversible, non-competitive inhibitor of the AT 1 receptor. Neither losartan nor its active metabolite inhibits ACE (kininase II, the enzyme that converts angiotensin I to angiotensin II and degrades bradykinin), nor do they bind to or block other hormone receptors or ion channels known to be important in cardiovascular regulation.
Who should not take it
Losartan potassium is contraindicated: • In patients who are hypersensitive to any component of this product. • For coadministration with aliskiren in patients with diabetes. • Hypersensitivity to any component. (4) • Coadministration with aliskiren in patients with diabetes. (4)
Warnings and cautions
• Hypotension: Correct volume or salt depletion prior to administration of losartan potassium. (5.2) • Monitor renal function and potassium in susceptible patients. (5.3 , 5.4) 5.1 Fetal Toxicity Losartan potassium can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When pregnancy is detected, discontinue losartan potassium as soon as possible [see Use in Specific Populations (8.1) ]. 5.2 Hypotension in Volume- or Salt-Depleted Patients In patients with an activated renin-angiotensin system, such as volume- or salt-depleted patients (e.g., those being treated with high doses of diuretics), symptomatic hypotension may occur after initiation of treatment with losartan potassium. Correct volume or salt depletion prior to administration of losartan potassium [see Dosage and Administration (2.1) ]. 5.3 Renal Function Deterioration Changes in renal function including acute renal failure can be caused by drugs that inhibit the renin angiotensin system and by diuretics. Patients whose renal function may depend in part on the activity of the renin-angiotensin system (e.g., patients with renal artery stenosis, chronic kidney disease, severe congestive heart failure, or volume depletion) may be at particular risk of developing acute renal failure on losartan potassium. Monitor renal function periodically in these patients. Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function on losartan potassium [see Drug Interactions (7.3) and Use in Specific Populations (8.7) ]. 5.4 Hyperkalemia Monitor serum potassium periodically and treat appropriately. Dosage reduction or discontinuation of losartan potassium may be required [see Adverse Reactions (6.1) ]. […]
Reported side effects
Most common adverse reactions (incidence ≥2% and greater than placebo) are: dizziness, upper respiratory infection, nasal congestion, and back pain. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Zydus Pharmaceuticals USA Inc. at 1-877-993-8779 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Hypertension Losartan potassium has been evaluated for safety in more than 3300 adult patients treated for essential hypertension and 4058 patients/subjects overall. Over 1200 patients were treated for over 6 months and more than 800 for over one year. Treatment with losartan potassium was well-tolerated with an overall incidence of adverse events similar to that of placebo. In controlled clinical trials, discontinuation of therapy for adverse events occurred in 2.3% of patients treated with losartan potassium and 3.7% of patients given placebo. In 4 clinical trials involving over 1000 patients on various doses (10 to 150 mg) of losartan potassium and over 300 patients given placebo, the adverse events that occurred in ≥2% of patients treated with losartan potassium and more commonly than placebo were: dizziness (3% vs. 2%), upper respiratory infection (8% vs. 7%), nasal congestion (2% vs. 1%), and back pain (2% vs. 1%). The following less common adverse reactions have been reported: Blood and lymphatic system disorders: Anemia. Psychiatric disorders: Depression. Nervous system disorders: Somnolence, headache, sleep disorders, paresthesia, migraine. Ear and labyrinth disorders: Vertigo, tinnitus. Cardiac disorders: Palpitations, syncope, atrial fibrillation, CVA. Respiratory, thoracic and mediastinal disorders: Dyspnea. Gastrointestinal disorders: Abdominal pain, constipation, nausea, vomiting. Skin and subcutaneous tissue disorders: Urticaria, pruritus, rash, photosensitivity. Musculoskeletal and connective tissue disorders: Myalgia, arthralgia. […]
Interactions with other medicines
• Agents Increasing Serum Potassium: Risk of hyperkalemia. (7.1) • Lithium: Risk of lithium toxicity. (7.2) • NSAIDs: Increased risk of renal impairment and reduced diuretic, natriuretic, and antihypertensive effects. (7.3) • Dual Inhibition of the Renin-Angiotensin System: Increased risk of renal impairment, hypotension, syncope, and hyperkalemia. (7.4) 7.1 Agents Increasing Serum Potassium Coadministration of losartan with other drugs that raise serum potassium levels may result in hyperkalemia. Monitor serum potassium in such patients. 7.2 Lithium Increases in serum lithium concentrations and lithium toxicity have been reported during concomitant administration of lithium with angiotensin II receptor antagonists. Monitor serum lithium levels during concomitant use. 7.3 Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Including Selective Cyclooxygenase-2 Inhibitors (COX-2 Inhibitors) In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, coadministration of NSAIDs, including selective COX-2 inhibitors, with angiotensin II receptor antagonists (including losartan) may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving losartan and NSAID therapy. The antihypertensive effect of angiotensin II receptor antagonists, including losartan, may be attenuated by NSAIDs, including selective COX-2 inhibitors. 7.4 Dual Blockade of the Renin-Angiotensin System (RAS) Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, syncope, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. The Veterans Affairs Nephropathy in Diabetes (VA NEPHRON-D) trial enrolled 1448 patients with type 2 diabetes, elevated urinary-albumin-to-creatinine ratio, and decreased estimated glomerular filtration rate (GFR 30 to 89.9 mL/min), randomized them to lisinopril or placebo on a background of losartan therapy and followed them for a median of 2.2 years. […]
Use in specific groups
• Losartan potassium is not recommended in pediatric patients less than 6 years of age or in pediatric patients with glomerular filtration rate less than 30 mL/min/1.73 m 2 . (2.1 , 8.4) • Hepatic Impairment: Recommended starting dose 25 mg once daily. (2.4 , 8.8 , 12.3) 8.1 Pregnancy Risk Summary Losartan potassium can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents. When pregnancy is detected, discontinue losartan potassium as soon as possible (see Clinical Considerations). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Clinical Considerations Disease-associated Maternal and/or Embryo/Fetal Risk Hypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death. Pregnant women with hypertension should be carefully monitored and managed accordingly. Fetal/Neonatal Adverse Reactions Oligohydramnios in pregnant women who use drugs affecting the renin-angiotensin system in the second and third trimesters of pregnancy can result in the following: reduced fetal renal function leading to anuria and renal failure, fetal lung hypoplasia, skeletal deformations, including skull hypoplasia, hypotension, and death. […]
If too much is taken
Significant lethality was observed in mice and rats after oral administration of 1000 mg/kg and 2000 mg/kg, respectively, about 44 and 170 times the maximum recommended human dose on a mg/m 2 basis. Limited data are available in regard to overdosage in humans. The most likely manifestation of overdosage would be hypotension and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatic hypotension should occur, supportive treatment should be instituted. Neither losartan nor its active metabolite can be removed by hemodialysis.
Before you take anything new
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This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 22 October 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.