Losartan is one of the most widely used blood pressure medicines worldwide. As the first angiotensin II receptor blocker (ARB) to reach the market, it helped redefine hypertension care by lowering blood pressure without the dry cough commonly associated with ACE inhibitors. Beyond hypertension, losartan’s organ-protective benefits extend to the kidneys and heart, making it a cornerstone in modern cardiovascular and renal risk reduction. If you have elevated blood pressure, diabetes with protein in the urine, or certain forms of heart disease, losartan may be part of a safe, effective, and well-tolerated plan recommended by your clinician.
Losartan is an angiotensin II receptor blocker (ARB) indicated for the treatment of hypertension in adults and in pediatric patients 6 years and older. By selectively blocking the AT1 receptor, losartan prevents angiotensin II from constricting blood vessels and from stimulating aldosterone, a hormone that promotes sodium and water retention. The result is vasodilation, reduced blood volume, decreased afterload, and a smoother workload on the heart. Most patients experience meaningful blood pressure reductions, and many see additional benefits when losartan is combined with a thiazide diuretic or a calcium channel blocker for comprehensive blood pressure control.
In patients with type 2 diabetes and evidence of kidney involvement (such as protein in the urine), losartan lowers intraglomerular pressure and reduces proteinuria, slowing the decline in kidney function. This renal-protective effect is a key reason clinicians choose an ARB like losartan over other classes when diabetic nephropathy is present or suspected. Losartan also plays a role in heart failure with reduced ejection fraction for patients who are unable to tolerate ACE inhibitors, helping ease symptoms and reduce hospitalizations when used as part of guideline-based therapy.
Another clinically relevant benefit is losartan’s uricosuric effect: it can lower serum uric acid. For patients with hypertension and gout or hyperuricemia, losartan may be especially appealing compared with other ARBs that do not share this feature. In select patients with left ventricular hypertrophy (LVH), losartan-based regimens have been used to reduce the risk of stroke. Overall, losartan is versatile, with a favorable tolerability profile and robust evidence in cardiovascular and renal protection that extends beyond its blood pressure–lowering capabilities.
Losartan is typically taken once daily, with or without food, at the same time each day. For most adults with primary hypertension, the usual starting dose is 50 mg once daily. Depending on blood pressure response, it may be increased to a maximum of 100 mg daily, either as a single dose or divided into two doses. Patients who are volume-depleted (for example, from vigorous diuretic use), older adults, or those with hepatic impairment often start at 25 mg once daily to reduce the risk of initial dizziness or hypotension.
Indication-specific guidance: - Hypertension (adults): Start 50 mg once daily; adjust to 25–100 mg daily based on response and tolerability. Combination with thiazide diuretics (e.g., hydrochlorothiazide/losartan) can enhance blood pressure control, especially in resistant hypertension. - Diabetic nephropathy (type 2 diabetes with proteinuria): Start 50 mg once daily, titrating to 100 mg daily as tolerated to maximize renal protection. - Heart failure (when ARB is indicated): Start 25 mg once daily; uptitrate to 50–100 mg daily as tolerated, in line with the broader heart failure regimen (which may include a beta-blocker, diuretic, and mineralocorticoid receptor antagonist). - Pediatric hypertension (6 to 16 years): Typical starting dose is 0.7 mg/kg once daily (up to 50 mg). Dosing should be individualized by a pediatric specialist, with careful monitoring of renal function and potassium.
Special populations and adjustments: - Hepatic impairment: Consider a lower starting dose (25 mg daily) due to reduced metabolism and higher exposure to the active metabolite. - Renal impairment: No routine dose adjustment is required, but monitoring of renal function and potassium is essential. In bilateral renal artery stenosis or severe chronic kidney disease, initiation and titration should be cautious. - Black patients: ARBs as monotherapy may achieve slightly less blood pressure reduction compared to some other groups; combination therapy often yields the best results. This is a population-level observation and should not deter individualized use when clinically appropriate.
Directions for best results: - Take losartan consistently, preferably at the same time daily. - If you experience lightheadedness when standing, especially after the first doses, rise slowly and discuss with your clinician; a dose adjustment may help. - Do not use salt substitutes high in potassium unless instructed, and be mindful of high-potassium diets if your clinician is monitoring your potassium levels. - Continue lifestyle measures (DASH-style eating pattern, sodium reduction, regular activity, weight management, limited alcohol), which work synergistically with losartan to improve blood pressure and long-term outcomes. - Never stop losartan abruptly without medical advice; uncontrolled hypertension can cause serious complications.
Pregnancy: Losartan carries a boxed warning for fetal toxicity. ARBs can harm or terminate a developing fetus, particularly in the second and third trimesters, by affecting renal perfusion and development. If pregnancy is planned or suspected, consult your clinician immediately. Therapy should be discontinued as soon as pregnancy is detected and replaced with an alternative that is safe for pregnancy. For patients of childbearing potential, discuss reliable contraception and preconception planning before starting therapy.
Kidneys and electrolytes: Like other agents that act on the renin–angiotensin system, losartan can raise potassium and affect kidney function, especially in patients with chronic kidney disease, diabetes, heart failure, or dehydration. Your clinician will typically check serum creatinine and potassium within 1–2 weeks of starting or adjusting the dose, then periodically. Notify your clinician if you experience decreased urine output, profound fatigue, muscle weakness, or heart palpitations, which may indicate high potassium or kidney issues. Patients with bilateral renal artery stenosis or a single functioning kidney require careful supervision.
Blood pressure effects and volume status: Symptomatic hypotension can occur, particularly if you are volume depleted (for example, after aggressive diuresis, vomiting, or diarrhea). Hydrate appropriately and report lightheadedness or fainting. Before surgeries or procedures that involve anesthesia, inform your surgical team that you take an ARB; your clinician may advise holding or continuing the dose based on current guidelines and your cardiovascular status. In general, losartan does not cause cough and angioedema is rare, but any facial or tongue swelling, breathing difficulty, or hives requires urgent medical attention.
Losartan is contraindicated in pregnancy and in patients with known hypersensitivity to losartan or any component of the formulation. Concomitant use of aliskiren with losartan is contraindicated in patients with diabetes due to an increased risk of renal impairment, hyperkalemia, and hypotension. Dual blockade of the renin–angiotensin system by combining an ARB with an ACE inhibitor is generally discouraged because of increased adverse effects without added clinical benefit for most patients; if considered in highly select cases, it requires specialist oversight and close monitoring.
Most people tolerate losartan well. The most commonly reported side effects are generally mild and transient, including dizziness, fatigue, nasal congestion, and back pain. Gastrointestinal upset such as diarrhea can occur. Because losartan lowers blood pressure, some patients feel lightheaded when standing, especially early in treatment or after a dose increase; this often improves as your body adjusts. Taking the medicine at night or reducing the dose temporarily may be helpful under medical guidance.
Less common but clinically important adverse effects include hyperkalemia (elevated potassium), worsening kidney function, and, rarely, angioedema. Signs of high potassium can include muscle weakness or an unusual heartbeat; laboratory monitoring is the most reliable way to detect changes early. Kidney effects are more likely in patients with preexisting renal impairment, dehydration, or renal artery stenosis. Although far less frequent than with ACE inhibitors, angioedema has been reported with ARBs and requires immediate emergency care if it occurs.
Seek medical attention promptly if you experience: - Fainting, severe dizziness, or confusion. - Swelling of the face, lips, tongue, or throat; difficulty breathing. - Little or no urine output, swelling in the legs, or sudden weight gain. - Persistent palpitations or chest pain. Most minor side effects improve as therapy continues or after a dose adjustment. Never stop or change your medication without contacting your clinician, as unmanaged hypertension can lead to stroke, heart attack, and kidney damage.
Losartan’s safety profile depends on thoughtful management of drug and dietary interactions, especially those affecting potassium and kidney function. Always provide your healthcare team with a complete list of prescription medications, over-the-counter drugs, vitamins, and herbal supplements.
Key interactions and considerations: - Potassium-elevating agents: Potassium supplements, potassium-sparing diuretics (spironolactone, eplerenone, amiloride), and salt substitutes containing potassium can raise serum potassium when combined with losartan. This combination may be appropriate in specific heart failure scenarios, but it demands close monitoring. - NSAIDs: Nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen, high-dose aspirin) can blunt losartan’s antihypertensive effect and increase the risk of kidney injury, particularly in older adults, dehydrated patients, or those with CKD. If you need pain relief, discuss safer alternatives such as acetaminophen or topical agents when appropriate. - Lithium: ARBs can increase lithium levels and toxicity risk. If combined, lithium levels require frequent monitoring and dose adjustments. - Diuretics: Thiazide or loop diuretics often enhance blood pressure control with losartan. However, volume depletion can precipitate symptomatic hypotension, especially at initiation. - Aliskiren and ACE inhibitors: Avoid aliskiren with losartan in diabetes; dual blockade with ACE inhibitors is generally not recommended due to increased risk of renal impairment and hyperkalemia without clear added benefit for most patients.
Metabolism-related interactions: - Losartan is metabolized by CYP2C9 and CYP3A4 to an active metabolite. Strong enzyme inducers (e.g., rifampin) may reduce losartan’s effect; certain inhibitors (e.g., fluconazole) can alter levels of the active metabolite. Clinicians typically account for these effects when selecting doses. - Grapefruit juice does not carry a well-established, clinically significant interaction with losartan, but moderation is sensible in polypharmacy settings. - Alcohol can amplify blood pressure–lowering effects and dizziness; limit intake and avoid hazardous activities until you know how you respond. When in doubt, consult your clinician or pharmacist before adding new medications or supplements. Simple checks up front can prevent potentially serious interactions down the line.
If you miss a dose of losartan, take it as soon as you remember the same day. If it is close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not double up to make up for a missed dose. If you miss doses frequently, consider setting phone reminders or using a pill organizer to stay on track.
Symptoms of losartan overdose may include pronounced dizziness, fainting, rapid or slow heart rate, and, in severe cases, shock from low blood pressure. If an overdose is suspected, call emergency services or contact Poison Control right away. Supportive care is the mainstay of management. Do not attempt to self-treat hypotension by consuming large volumes of fluid or salt without medical advice, especially if you have heart failure, kidney disease, or other conditions where fluid balance is critical.
Store losartan tablets at room temperature, ideally 20–25°C (68–77°F), away from moisture, heat, and direct light. Keep tablets in their original, tightly closed container, and use a dry hand to remove doses to prevent degradation. Do not store medications in humid bathrooms. For travel, keep losartan in your carry-on bag with the original label. Safely discard expired or unused medication through a community medication take-back program; do not flush unless specifically instructed.
Blood pressure improvement with losartan usually begins within the first week, with full effect often seen by three to six weeks. Kidney protection and reductions in proteinuria may take longer to demonstrate on lab testing. Your clinician will typically monitor blood pressure, kidney function (serum creatinine and eGFR), and potassium within one to two weeks after starting or changing the dose, then at intervals based on your stability and risk profile. Home blood pressure logs, recorded at a consistent time each day, provide invaluable information for fine-tuning therapy.
Many patients notice they feel no different when blood pressure is better controlled, which is expected—hypertension is often silent. Signs that your treatment is working include improved blood pressure readings and favorable lab trends. Notify your clinician if you develop frequent lightheadedness, new swelling, changes in urination, or muscle weakness. If blood pressure remains above target despite adherence and lifestyle changes, your clinician may adjust the dose or add a complementary medication, such as a thiazide diuretic or amlodipine, to reach guideline-recommended goals.
In the United States, losartan is a prescription-only medication. It should be started, adjusted, and monitored by a licensed clinician who can evaluate your medical history, risk factors, and lab results. Purchasing or using prescription medicines without a valid prescription is unsafe and may be illegal. Any legitimate pathway to obtain losartan includes a clinician’s evaluation and an authorized prescription sent to a licensed pharmacy.
Physician House Calls of Kansas offers a legal and structured way to access care for conditions like high blood pressure and diabetic kidney disease. Through in-home visits or telehealth, their clinicians can assess your symptoms, review medications, check vitals, and order necessary labs. If losartan is appropriate for you, they can issue a compliant prescription and route it to your preferred pharmacy—no waiting rooms, and no gray-market vendors. This model preserves safety and quality while improving convenience.
What this means for you: you can explore treatment options quickly and responsibly. Schedule a consultation, complete your evaluation, and, if indicated, receive an e-prescription for losartan or a therapeutic alternative. This approach respects U.S. regulations, protects your health with proper monitoring, and provides an accessible route to evidence-based care, especially if traditional clinic visits are difficult.
Losartan is an angiotensin II receptor blocker (ARB) that relaxes blood vessels by blocking the AT1 receptor, lowering blood pressure and easing the workload on the heart while reducing harmful effects of angiotensin II on the kidneys and blood vessels.
It is used to treat high blood pressure, slow kidney damage in adults with type 2 diabetes and proteinuria, and lower the risk of stroke in people with hypertension and left ventricular hypertrophy; it’s also used off-label when ACE inhibitors aren’t tolerated.
Take it once daily, with or without food, at the same time each day; morning or evening is fine—choose the time you can stick to consistently, and if you feel dizzy after dosing, consider taking it at night.
Most adults start at 50 mg once daily (25 mg if volume-depleted, elderly, or with liver impairment) and titrate to 100 mg daily; some people benefit from splitting the dose into 50 mg twice daily for smoother 24-hour control.
You’ll see some effect within hours, with full blood pressure–lowering benefits developing over 1–4 weeks as the body reaches steady state and blood vessels remodel.
Dizziness, fatigue, low blood pressure, and elevated potassium are most common; less often it can affect kidney function or cause rare angioedema—seek urgent care for swelling of the face, lips, or tongue.
Cough is uncommon with ARBs; if you developed a dry cough on an ACE inhibitor, losartan is often a good alternative because it does not increase bradykinin.
Yes, losartan can raise potassium; avoid potassium supplements and salt substitutes containing potassium unless your clinician is monitoring your levels and has approved them.
It is not safe in pregnancy and carries a boxed warning for fetal toxicity—stop it and contact your clinician immediately if you become pregnant; it’s generally not recommended during breastfeeding, especially with newborns, due to limited safety data.
Yes, in type 2 diabetes with proteinuria it lowers albuminuria and slows progression of diabetic kidney disease, partly by lowering intraglomerular pressure and reducing inflammation and fibrosis.
Losartan is the only ARB with a uricosuric effect; it can modestly lower serum uric acid and may reduce gout flares, which makes it attractive if you have hypertension plus gout.
NSAIDs can blunt blood pressure control and raise kidney risk, lithium levels can rise, and potassium-sparing diuretics or potassium supplements increase hyperkalemia risk; avoid aliskiren if you have diabetes, and large amounts of grapefruit may alter metabolism in some people.
Alcohol can amplify dizziness and drop blood pressure, so use cautiously; moderate coffee is generally fine, though caffeine can transiently raise blood pressure—monitor your readings and how you feel.
Check blood pressure at home, and get kidney function (creatinine, eGFR) and potassium tested within 1–2 weeks after starting or changing dose, then periodically based on your risk profile.
Take the missed dose when you remember unless it’s close to the next dose—don’t double up; don’t stop abruptly without a plan, as blood pressure can rebound—discuss tapering or switching with your clinician.
Both are effective once-daily ARBs; valsartan tends to be slightly more potent milligram-for-milligram and may provide firmer trough control, while losartan may require higher doses or twice-daily splitting for persistent 24-hour coverage in some patients.
Both have strong evidence in type 2 diabetes with proteinuria (losartan in RENAAL, irbesartan in IDNT); choice often depends on tolerance, cost, and desired extras—losartan lowers uric acid, while irbesartan provides robust albuminuria reduction at 300 mg daily.
Candesartan has a longer half-life and often delivers steadier 24-hour blood pressure control; it also has strong heart failure outcome data, whereas losartan is used off-label when ACE inhibitors aren’t tolerated and may need BID dosing for durability.
Telmisartan’s very long half-life (~24 hours) offers excellent morning-to-morning coverage and has modest insulin-sensitizing effects; losartan’s unique advantage is uric acid lowering, with a shorter half-life that sometimes warrants split dosing.
Olmesartan is among the most potent ARBs for blood pressure and is reliably once daily, but carries a rare risk of sprue-like enteropathy (chronic diarrhea and weight loss); losartan is less potent per milligram but lacks that specific GI risk and lowers uric acid.
Azilsartan is one of the most powerful ARBs for blood pressure reduction with strong 24-hour effect, but may be pricier or less widely covered; losartan is broadly available and cost-effective, with the added gout-friendly uricosuric effect.
Eprosartan often needs twice-daily dosing and is used less commonly today; losartan is typically once daily, has more outcome data (renal protection, stroke risk reduction in LVH), and is easier to source generically.
Telmisartan generally provides superior early-morning control due to its long half-life; if morning readings remain high on losartan, options include increasing the dose, switching to telmisartan, or splitting losartan to twice daily.
Valsartan has labeled indications for heart failure and post–myocardial infarction; losartan is often used off-label when ACE inhibitors aren’t tolerated but has less definitive outcome data in these settings.
Losartan is preferred if lowering uric acid is a goal; irbesartan is uric acid–neutral, making losartan the better choice for patients with hypertension plus gout risk.
Candesartan has randomized trial evidence for migraine prophylaxis and is commonly used off-label; losartan has less robust data, so candesartan is generally favored for migraine prevention among ARBs.
No single ARB is “best” for everyone; selection is individualized based on blood pressure targets, 24-hour control needs, kidney disease, heart failure or post-MI indications, uric acid concerns, side-effect profile, dosing preference, and cost/access—losartan remains a strong first-line, especially when gout or diabetic nephropathy coexists.