Losartan: Uses, Side Effects, Dosage & Safety

Losartan is one of the most commonly prescribed blood pressure medicines in the United States, and it is also one of the most misunderstood. People often ask whether it is a water pill (it isn’t), whether it causes the cough that comes with lisinopril (much less often), and whether the old losartan recalls are still a concern (they are not, as far as FDA records show). This article answers those questions and walks through what the prescribing information actually says about doses, side effects, and interactions.

It is written for people who have been prescribed losartan, are caring for someone who has, or want to understand the drug before starting it. Everything here is general information, not a substitute for the instructions you got from your own prescriber.

Losartan is an angiotensin II receptor blocker (ARB) used to lower blood pressure, to reduce stroke risk in some people with an enlarged heart muscle, and to slow kidney damage in type 2 diabetes. The usual adult starting dose is 50 mg once daily, with a maximum of 100 mg once daily. Common side effects are mild (dizziness, stuffy nose), but losartan can raise potassium, strain the kidneys in vulnerable people, and must not be used during pregnancy. Do not stop it on your own, and tell your prescriber right away if you become pregnant.

What losartan does in the body

Your body makes a hormone called angiotensin II that tightens blood vessels and signals the adrenal glands to release aldosterone, which makes the kidneys hold on to salt and water. Both effects push blood pressure up. Losartan blocks angiotensin II from attaching to its main receptor (the AT1 receptor), so blood vessels stay more relaxed and less salt and water are retained.

Two details from the prescribing information are worth knowing. First, only a portion of each dose (about 14%) is converted by liver enzymes into a more potent active form, and that metabolite does most of the blocking. The parent drug has a half-life of about 2 hours, while the active metabolite lasts roughly 6 to 9 hours, which is why a once-a-day schedule works. Second, losartan does not interfere with the breakdown of bradykinin, the compound ACE inhibitors allow to build up. That difference helps explain why cough is much less of a problem with ARBs than with drugs like lisinopril.

Losartan is not a diuretic. The combination pill called Hyzaar contains losartan plus hydrochlorothiazide (a water pill), which is a separate drug with its own side effects.

What losartan is approved to treat

The FDA-approved prescribing information for losartan lists three uses:

• High blood pressure in adults and in children 6 years and older. Lowering blood pressure reduces the risk of strokes and heart attacks, and losartan is one of many drug classes with that evidence. If you want a refresher on what the numbers mean, Healthfity’s guide to high blood pressure and its stages is a good place to start.
• Stroke risk reduction in hypertension with left ventricular hypertrophy (LVH), meaning a thickened heart muscle seen on an ECG.
• Diabetic kidney disease: in people with type 2 diabetes, a history of high blood pressure, elevated creatinine, and a urine albumin-to-creatinine ratio of 300 mg/g or more.

The 2025 AHA/ACC high blood pressure guideline lists ARBs among the four first-line drug classes, alongside ACE inhibitors, thiazide-type diuretics, and long-acting calcium channel blockers. Which one a clinician picks often depends on other conditions: ARBs and ACE inhibitors are especially common choices when someone also has diabetes with kidney involvement.

What the major trials showed

The LIFE trial enrolled 9,193 people with hypertension and LVH and compared losartan with atenolol. Over about 4.8 years, the losartan group had a 13% lower risk of the combined outcome of cardiovascular death, stroke, or heart attack, driven mainly by a 25% lower risk of stroke. There was no meaningful difference in heart attacks. Black participants made up only 6% of the trial, and in that small subgroup the atenolol group did better. The label states that this result may be due to chance but that LIFE provides no evidence that losartan’s benefit applies to Black patients. This is why you will see a caution in the prescribing information, and it is a reason some clinicians reach for other options in that specific situation.

The RENAAL trial followed 1,513 people with type 2 diabetes and kidney disease for an average of 3.4 years. Losartan reduced the risk of doubling of serum creatinine, kidney failure, or death by 16%. Looked at separately, doubling of creatinine fell by 25% and end-stage kidney disease by 29%, and protein in the urine dropped by an average of 34%. Overall death rates did not change.

Losartan dosage

Your dose is chosen by your prescriber. This section describes what the prescribing information says so you can follow the reasoning, not so you can adjust your own dose.

• Adult hypertension: usual starting dose 50 mg once daily, up to 100 mg once daily if needed. The label recommends a lower starting dose of 25 mg for people who may be low on fluid or salt, such as those already taking a diuretic.
• Hypertension with LVH: start at 50 mg daily. If blood pressure is not controlled, hydrochlorothiazide 12.5 mg is added and/or the losartan dose goes to 100 mg.
• Diabetic kidney disease: start at 50 mg daily, increasing to 100 mg depending on blood pressure response.
• Liver impairment: mild to moderate impairment calls for a 25 mg starting dose, because blood levels of losartan run about five times higher. It has not been studied in severe liver impairment.
• Kidney impairment: no adjustment is needed on its own, unless the person is also low on fluids.
• Children 6 to 16: a starting dose of 0.7 mg per kilogram once daily, up to 50 mg total, as a tablet or a pharmacist-prepared liquid. Losartan is not recommended under age 6 or when kidney filtration is below 30 mL/min/1.73 m2.

Tablets come in 25, 50, and 100 mg strengths. MedlinePlus notes that it is usually taken once or twice a day, with or without food, at about the same time each day. In the clinical studies behind the label, splitting the same total daily dose into two doses gave a somewhat larger effect at the end of the dosing interval, so some prescribers use a twice-daily schedule.

In the pivotal studies summarized in the prescribing information, 50 to 100 mg daily lowered blood pressure by about 5.5 to 10.5 mm Hg (systolic) and 3.5 to 7.5 mm Hg (diastolic) compared with placebo. Adding hydrochlorothiazide 12.5 mg to losartan 50 mg lowered it by about 15.5/9.2 mm Hg. A 150 mg dose did no better than 50 to 100 mg. In practice, some effect appears within a week, but the full effect can take 3 to 6 weeks.

A missed dose is usually handled the same way as with most once-daily medicines: take it when you remember, unless it is almost time for the next one, and never double up. Your pharmacist can confirm what applies to your product.

What to expect when you start

The first few weeks are mostly about two things: how your blood pressure responds and whether you feel dizzy. Lightheadedness, particularly when standing up quickly, is more likely early on, and MedlinePlus specifically warns that fainting can happen. Standing up slowly, staying hydrated, and avoiding sudden changes in position help.

Because losartan can affect kidney function and potassium, clinicians commonly check blood tests (creatinine and potassium) after starting or changing a dose, and again periodically. The label calls for periodic monitoring in people at higher risk, such as those with chronic kidney disease, severe heart failure, or narrowed kidney arteries.

Home blood pressure readings are worth keeping. A written log lets your clinician see whether the dose is working, and it makes it easier to spot a problem if your readings suddenly change.

Losartan controls high blood pressure but does not cure it. Stopping suddenly is not a good idea even if you feel well, because pressure usually drifts back toward where it was. The label does not describe a rebound spike after abrupt withdrawal, but the underlying hypertension is still there. If a side effect is bothering you, call your prescriber instead of quietly skipping doses.

Losartan side effects

Losartan is generally well tolerated. In the placebo-controlled studies in the prescribing information, treatment was stopped because of side effects in 2.3% of people on losartan and 3.7% on placebo. The side effects that occurred in at least 2% of losartan users and more often than with placebo were:

• Dizziness (3% vs. 2%)
• Upper respiratory infection (8% vs. 7%)
• Nasal congestion (2% vs. 1%)
• Back pain (2% vs. 1%)

Less common effects reported in trials include headache, sleepiness, vertigo, ringing in the ears, palpitations, nausea, constipation, rash, itching, muscle or joint pain, swelling, anemia, and sexual dysfunction. In the RENAAL trial of people with diabetic kidney disease, tiredness, low blood pressure on standing, diarrhea, anemia, and high potassium were more common with losartan, which fits the population: people with kidney disease are more prone to these changes.

The effects worth understanding

High potassium (hyperkalemia). Blocking angiotensin II lowers aldosterone, which can let potassium build up. In otherwise healthy people with high blood pressure, the label notes very little effect on potassium. Risk rises with kidney disease, diabetes, and certain other drugs (see interactions). For this reason, the label advises against potassium supplements or potassium-based salt substitutes unless your clinician okays them.

Low blood pressure and kidney strain. If you are dehydrated or salt-depleted, losartan can cause symptomatic low blood pressure and, in vulnerable people, acute kidney injury. This is why the label recommends correcting volume depletion first, and why persistent vomiting or diarrhea deserves a call to your prescriber. Healthfity’s articles on chronic dehydration and diarrhea and red flags explain how to recognize fluid loss.

Cough. The prescribing information describes two studies of people who had developed an ACE inhibitor cough. When those people were rechallenged, cough returned in roughly 62 to 69% of those given lisinopril but in about 17 to 29% of those on losartan, a rate similar to the comparison groups (hydrochlorothiazide or placebo). Cough can still be reported with losartan, but it is not the typical problem.

Angioedema. Swelling of the face, lips, tongue, or throat has been reported rarely, including in some people who previously had it with ACE inhibitors. It can affect breathing and needs emergency care.

Other rare events reported after the drug reached the market include hepatitis, low platelets, a type of blood vessel inflammation (Henoch-Schonlein purpura), anaphylaxis, low sodium, muscle breakdown (rhabdomyolysis), and a severe skin reaction called erythroderma. If you ever notice yellowing of the skin or eyes, unexplained severe muscle pain, a spreading rash, or trouble breathing or swallowing, seek medical care promptly. For a wider look at warning signs that should never be ignored, see Healthfity’s piece on heart health warning signs.

Pregnancy, breastfeeding, and other cautions

Pregnancy. Losartan carries a boxed warning for fetal toxicity. Drugs that act on the renin-angiotensin system, used during the second and third trimesters, can reduce fetal kidney function and cause low amniotic fluid, which in turn is linked to underdeveloped lungs, skull and skeletal problems, newborn kidney failure, and death. The label directs that losartan be discontinued as soon as pregnancy is detected. If you are pregnant, planning pregnancy, or could become pregnant, talk with your prescriber now so a safer alternative can be arranged under supervision.

Breastfeeding. It is not known whether losartan passes into human milk; it does enter rat milk. The label leaves the decision to weigh the benefits to the mother against possible risks to the baby, which is a conversation for your clinician.

Kidney disease, heart failure, or renal artery narrowing. These increase the chance that losartan will worsen kidney function, so monitoring is more important.

Diabetes. Losartan is not combined with the drug aliskiren in people with diabetes, and the label advises avoiding that pairing when kidney filtration is below 60. If you take diabetes medicine such as metformin, losartan is commonly part of the regimen for kidney protection, and the two do not have a documented interaction.

Older adults. In the clinical studies, overall safety and effectiveness were similar in people 65 and older, though greater sensitivity in some older individuals cannot be ruled out.

Gout. Losartan has a mild uric-acid-lowering effect. The 2020 American College of Rheumatology gout guideline conditionally recommends choosing losartan preferentially as an antihypertensive in people with gout and switching away from hydrochlorothiazide when feasible, though the certainty of the evidence was rated very low. The American Family Physician summary of that guideline says the same. The effect is small, so it does not replace gout treatment.

Interactions

• Potassium supplements, potassium-based salt substitutes, and potassium-raising drugs. These can push potassium too high. Do not start them without checking with your clinician.
• NSAIDs. In older adults, people low on fluids, and people with reduced kidney function, NSAIDs can worsen kidney function when taken with losartan, and they can blunt its blood-pressure-lowering effect. If you use ibuprofen or naproxen, ask your pharmacist whether it is safe for you and what to use for pain instead. People who take NSAIDs for joint pain, for example with arthritis, should especially have that conversation.
• Other renin-angiotensin drugs (ACE inhibitors, other ARBs, aliskiren). The VA NEPHRON-D trial added lisinopril to losartan in 1,448 people with diabetic kidney disease. There was no added benefit for kidney outcomes, and hyperkalemia and acute kidney injury occurred more often. Combining these drugs is generally avoided.
• Lithium. Levels can rise to toxic levels, so lithium blood levels need monitoring.
• Diuretics and other blood pressure drugs. These add to the blood-pressure-lowering effect, which is often intended but can cause lightheadedness.
• Drugs that affect liver enzymes. Rifampin lowered levels of losartan and its active metabolite by about 30% and 40%. Fluconazole, which blocks the CYP2C9 enzyme, raised losartan levels by about 70% but reduced the active metabolite by about 40%, and the clinical effect has not been examined. MedlinePlus also lists phenobarbital among drugs to mention to your prescriber.

Always give your pharmacist a full list of medicines and supplements, including over-the-counter products.

Losartan compared with ACE inhibitors and other ARBs

ACE inhibitors (like lisinopril) and ARBs (like losartan) both interrupt the same hormonal system, and both are first-line options. The practical differences are small but noticeable. ACE inhibitors are more likely to cause a dry cough because they allow bradykinin to accumulate. ARBs like losartan are often chosen when that cough appears, and angioedema, though rare, can occur with either. Both classes are avoided in pregnancy, both can raise potassium, and they should not routinely be taken together.

Losartan is one of several ARBs, along with valsartan, irbesartan, candesartan, olmesartan, telmisartan, and azilsartan. In the 2018 to 2019 period, some lots of valsartan, irbesartan, and losartan were recalled for impurities, which is why many patients were switched between ARBs. Whether one ARB suits you better than another depends on your other conditions, cost, and tolerance, and that is a decision for you and your prescriber.

Health habits still matter alongside any drug. Sodium intake, weight, exercise, alcohol, and sleep all affect pressure. Healthfity’s articles on everyday habits that can raise blood pressure and on obesity and its health risks cover the lifestyle side.

Is there a losartan recall right now?

This question comes up constantly because social media posts keep recirculating old recall lists. Here is what the FDA records show.

In 2018 and 2019, several manufacturers recalled lots of losartan and losartan/hydrochlorothiazide tablets after trace amounts of nitrosamine impurities were found in the active ingredient. Torrent’s recall involved N-nitrosodiethylamine (NDEA) in ingredient supplied by Hetero Labs, and Camber’s recall involved another impurity called NMBA across 87 lots. The FDA’s postings for the Torrent and Teva recalls now state that the recalls have been completed and terminated. Throughout, the companies and the FDA advised patients to keep taking their medicine until a replacement was available, because stopping blood pressure treatment can be more dangerous than the trace impurity.

In the recall roundups I checked in late October 2026, none listed a new losartan recall this year. Recall status can change, so if you are concerned about your own supply, read the manufacturer name and lot number on your bottle, ask your pharmacist whether it is affected, and search the FDA’s enforcement report. The FDA’s explanation of how drug recalls work describes the recall classes and what patients should do.

Overdose and reporting side effects

The most likely signs of a large overdose are low blood pressure and a fast heartbeat, and a slow heartbeat is possible too. If someone has taken too much, call Poison Control at 1-800-222-1222 or use the online tool at poisonhelp.org. If the person has collapsed, had a seizure, or cannot be awakened, call 911. You can report side effects or product quality problems to the FDA through MedWatch.

Frequently asked questions

What is losartan used for? It is used to treat high blood pressure, to reduce the risk of stroke in people with hypertension and left ventricular hypertrophy, and to slow kidney disease progression in people with type 2 diabetes who have kidney damage and protein in the urine.

Should I take losartan in the morning or at night? The label does not require a specific time. MedlinePlus advises taking it at around the same time each day, and some people take it once daily while others take it twice. Follow your prescriber’s instructions and pick a time you can remember.

How long does losartan take to work? Some blood pressure lowering is present within about a week, and the full effect can take 3 to 6 weeks, so your prescriber may wait a few weeks before changing the dose.

Does losartan cause a cough like lisinopril? Much less often. In studies of people who had ACE inhibitor cough, cough came back far less with losartan than with lisinopril and at a rate similar to placebo or hydrochlorothiazide. A cough can still occur, so mention a persistent one to your prescriber.

Can I take ibuprofen or naproxen with losartan? Sometimes, but NSAIDs can reduce losartan’s effect and increase the risk of kidney problems, especially in older adults, people who are dehydrated, and people with kidney disease. Ask your pharmacist before combining them.

Do I need to avoid salt substitutes? If your salt substitute contains potassium chloride, check first. The label advises against potassium supplements or potassium-containing salt substitutes unless your clinician approves, because losartan can increase potassium.

Can I stop losartan once my blood pressure is normal? A normal reading usually means the medicine is working, not that the underlying problem is gone. Stopping on your own often lets pressure rise again, so talk with your prescriber before making any change.

Is losartan safe during pregnancy? No. It carries a boxed warning for fetal harm, particularly in the second and third trimesters. Tell your prescriber immediately if you are or might be pregnant so that your treatment can be changed safely.

What should I do if I miss a dose? Take it when you remember unless it is nearly time for the next dose; then skip the missed one. Do not take two doses at once. If you miss doses often, ask your pharmacist about reminders or a schedule that fits your day.

Is losartan safe to take long term? In long-term follow-up studies summarized in the label, the blood pressure effect appeared to be maintained for up to a year, and the controlled trials included thousands of participants followed for years. Regular blood tests and check-ins help catch potassium or kidney changes early.

This article is for general information and does not replace advice from your doctor or pharmacist. Do not change or stop a prescribed medicine without speaking to the person who prescribed it.