Losartan — what it does and how to use it safely

Losartan is a common blood pressure pill that also helps protect kidneys for some people with diabetes. Think of it as a blocker that relaxes blood vessels so your heart doesn’t have to work as hard. Many doctors prefer losartan because it’s well tolerated and works for long-term blood pressure control.

Who usually gets losartan? People with high blood pressure, some cases of heart failure, and patients with protein in their urine from diabetic kidney disease. It’s not a one-size-fits-all drug, so your doctor will decide if it’s right for you.

Dosage and basic dosing tips

Typical adult dosing starts at 50 mg once a day. Depending on how you respond, the dose can be adjusted between 25 mg and 100 mg daily. Some patients take a single dose; others split it into morning and evening. If you have kidney problems or are older, your doctor may start lower and check labs sooner.

If you miss a dose, take it when you remember unless it’s almost time for the next one. Don’t double up to catch up. If you’re starting a new blood pressure medicine or changing doses, expect lightheadedness the first few days — stand up slowly and drink water if you feel faint.

Side effects, interactions, and important warnings

Common side effects are dizziness, tiredness, and sometimes stomach upset. Two things to watch for: high potassium (hyperkalemia) and a drop in kidney function. Symptoms like muscle weakness, unusual tiredness, or irregular heartbeat could mean high potassium — call your doctor.

Avoid potassium supplements and salt substitutes that contain potassium unless your clinician says it’s okay. Also be careful with NSAIDs (ibuprofen, naproxen) because they can blunt losartan’s effect and raise the risk of kidney trouble, especially if you’re dehydrated or on a diuretic. Combining ARBs like losartan with ACE inhibitors or aliskiren is usually avoided because of higher risks of low blood pressure, high potassium, and kidney problems.

Important: don’t take losartan if you’re pregnant or planning to become pregnant. Drugs in this class can harm a fetus. Tell your doctor right away if pregnancy is possible. If you develop swelling of the face, lips, tongue, or trouble breathing, seek emergency care — angioedema is rare but serious.

Routine checks matter. Get your blood pressure, kidney function (serum creatinine), and potassium checked before starting and again within 1–2 weeks after a dose change. After that, your provider will set a schedule based on your health.

If you’re worried about side effects or mixing medicines, bring a list of everything you take to the clinic. Small changes — switching pain relievers, adjusting salt intake, or adding a vitamin — can make a difference. Talk with your doctor before changing or stopping losartan; they can help you switch safely if needed.