Medicine reading guide
Losartan
Oral losartan potassium tablets; US labeling, including the specified compounded suspension where stated.
How it works
Losartan blocks the place where angiotensin II sends its vessel-tightening message. Blood vessels can relax, and the kidney’s salt-and-water signals also change. It can lower blood pressure and protect kidneys in certain people with diabetic kidney disease. It blocks a receptor; it does not stop ACE from making angiotensin II.
Original content record dated 2026-09-30. Educational draft; independent clinical review pending.
About the referenced label
Selected label version 2 · SPL effective date 2025-10-10 · Retrieved 2026-10-09.
Label record supplied by NorthStar RxLLC. This may be a repackager's record.
These dates describe the source record, not a clinical review of this explanation. The online label may change; this explanation has not been revalidated against the retained snapshot by this source check.
Uses / Symptoms
- High blood pressure
- Selected diabetic kidney disease
Effects
- Lowers blood pressure
- Can slow eligible diabetic kidney disease
Side effects
- Dizziness
- High potassium
- Kidney-function changes
Selected uses and effects; not a complete safety list. Consult the referenced product information.
Explore the Losartan mechanism GIF and named chapters →
Questions about Losartan
What is this medicine used for?
Losartan treats hypertension, lowers stroke risk in a defined population with hypertension and left-ventricular hypertrophy, and treats diabetic nephropathy with proteinuria in people with type 2 diabetes and hypertension. The stroke indication has a limitation for Black patients in the supporting study. Kidney protection should not be generalized to every kidney disorder.
Why might it be prescribed for me?
Losartan may fit a person needing blood-pressure treatment, particularly when an ACE inhibitor causes cough or when the labeled diabetic nephropathy indication applies. Pregnancy, hyperkalemia, volume depletion, and renal changes may make another strategy necessary. The treatment plan depends on the full clinical picture, not merely the presence of diabetes.
What improvement should I expect?
You may not feel blood-pressure improvement, so use repeated measurements. In eligible diabetic kidney disease, losartan can slow progression rather than repair all existing damage. The RENAAL trial reduced a combined renal endpoint but did not show a reduction in death overall. Benefit depends on the indication and continued monitoring.
How soon should it start working?
Some blood-pressure effect is present within the first week; maximum effect in trials could take 3–6 weeks. Assess a series of correctly taken readings, adherence, and tolerability. Kidney-protection outcomes develop over much longer periods and cannot be judged from feeling different after one tablet or from one laboratory result.
How will I know whether it is helping?
Follow blood pressure, creatinine or estimated filtration, and potassium after initiation and dose changes, then according to clinical risk. In diabetic nephropathy, urinary protein and renal trends help assess the condition over time. Report vomiting, diarrhea, poor intake, NSAID use, or symptomatic low pressure because these can change renal risk.
How does it work, in simple terms?
Losartan blocks the place where angiotensin II sends its vessel-tightening message. Blood vessels can relax, and the kidney’s salt-and-water signals also change. It can lower blood pressure and protect kidneys in certain people with diabetic kidney disease. It blocks a receptor; it does not stop ACE from making angiotensin II.
How much is usually taken, and how often?
For adult hypertension, the usual labeled start is 50 mg once daily, increasing if needed to 100 mg daily. A 25 mg start is recommended when intravascular volume is depleted or with mild-to-moderate hepatic impairment. Pediatric dosing is weight based. These ranges require a prescription-specific review rather than self-adjustment.
Should I take it with food?
Take losartan as prescribed, usually once daily at a consistent time. It may be taken with or without food. Follow the label on the dispensed formulation; a liquid may have separate measuring or shaking instructions. Do not change the amount because a single blood-pressure reading is higher or lower than usual.
What should I do if I miss a dose?
For losartan, follow the missed-dose instructions on your dispensed leaflet: generally take a remembered dose unless it is nearly time for the next, then skip it. Never double a dose. If an extra dose was taken, contact poison control or a clinician promptly. After vomiting, ask before repeating a dose because absorption is uncertain.
What if I accidentally take too much?
Too much losartan can cause dangerous cardiovascular effects, including very low blood pressure. Contact US Poison Control at 1-800-222-1222 promptly, even if symptoms have not yet appeared. Call 911 for collapse, seizure, trouble breathing, or inability to awaken. Keep the package, amount, and timing available; do not induce vomiting.
How long might treatment continue?
Losartan commonly controls a continuing condition rather than curing it, so treatment may last months or years. The indication determines the review plan: hypertension is assessed through readings, while heart or kidney indications may require additional clinical and laboratory review. Feeling better alone is not a reason to stop. Ask when the next review is due.
Can I stop when I feel better?
Do not stop losartan simply because you feel well or your pressure is controlled. The condition may still need treatment, and pressure can rise again. Unlike a beta blocker, its label does not specify a routine withdrawal taper, but a clinician should plan any switch. Pregnancy or serious reactions require the specific urgent instructions.
What side effects are common?
Dizziness is a recognized side effect. Potassium may rise and kidney function can worsen in susceptible circumstances, which may be silent until blood tests. Report faintness, reduced urine, or persistent symptoms. Losartan causes less ACE-inhibitor-type cough because it does not inhibit ACE, but a new cough still deserves assessment if troublesome.
Which symptoms need urgent help?
Get emergency help for trouble breathing, swelling of the tongue or throat, or collapse. Markedly reduced urine, severe weakness, or a concerning irregular heartbeat warrants prompt assessment. If pregnancy occurs, stop losartan and contact the prescriber immediately as directed by its fetal-toxicity warning; an alternative treatment should be arranged.
Can it interact with medicines or supplements?
Potassium supplements, potassium-containing salt substitutes, and potassium-sparing drugs may increase potassium. NSAIDs can reduce blood-pressure benefit and worsen renal function, especially with dehydration or diuretics. Lithium concentrations can rise. Combining losartan with ACE inhibitors or aliskiren increases risks; aliskiren is contraindicated with losartan in patients with diabetes.
What about alcohol, driving, and exercise?
Losartan can cause dizziness, especially when treatment changes, so avoid driving or hazardous machinery until you know how you respond. Rise gradually if lightheaded. Ask about alcohol because it may worsen symptoms or blood-pressure control. Physical activity can remain beneficial, but follow the plan for your heart condition rather than using symptoms or pulse alone to set an exercise limit.
What about pregnancy, breastfeeding, or fertility?
Losartan should not be taken during pregnancy because renin–angiotensin-system blockade can injure or kill the fetus. If pregnancy occurs, stop it and contact the prescriber immediately. The selected US label advises choosing between nursing and treatment because infant risk is uncertain. Plan pregnancy-compatible blood-pressure treatment with the clinician before conception.
Will I need tests or monitoring?
Follow blood pressure, creatinine or estimated filtration, and potassium after initiation and dose changes, then according to clinical risk. In diabetic nephropathy, urinary protein and renal trends help assess the condition over time. Report vomiting, diarrhea, poor intake, NSAID use, or symptomatic low pressure because these can change renal risk.
Is there a generic or a lower-cost option?
Losartan is available as a prescription generic; Cozaar is a familiar brand name. The actual price, insurance coverage, and local stock have not been checked here. A pharmacist can compare the exact strength and formulation, arrange refill coordination, and contact the prescriber if supply is interrupted. Do not stretch doses to make a pack last.
What if it is not helping?
Losartan blocks AT1 rather than inhibiting ACE, so it does not directly prevent bradykinin breakdown. This can make it an option when an ACE inhibitor causes cough. It is not automatically safer for potassium, renal perfusion, or pregnancy. Comparisons among ARBs require clinical outcome and dose context; receptor binding alone does not establish superiority. If the treatment seems ineffective, first review reliable measurements, adherence, timing, and tolerability with the clinician. Do not switch or add another cardiovascular medicine yourself.