Losartan: what it treats and why people take it

Losartan is an angiotensin II receptor blocker (ARB) commonly used for high blood pressure, protecting the kidneys in type 2 diabetes, and helping some heart-failure patients. It lowers blood pressure by relaxing blood vessels so the heart pumps easier. Many doctors pick losartan when patients can't tolerate ACE inhibitors or need extra kidney protection.

How to take losartan safely

Typical adult dosing for hypertension starts at 25–50 mg once daily. Most people take 50 mg once a day and the dose can be raised up to 100 mg if needed. Take it at the same time each day, with or without food. If you miss a dose, take it when you remember unless it’s close to your next dose — don’t double up.

Before starting, your doctor should check your blood pressure, kidney function (serum creatinine), and potassium level. Repeat tests are usually done 1–2 weeks after starting or after a dose change. That helps catch drops in kidney function or high potassium early.

Common side effects, warnings, and interactions

Most side effects are mild: dizziness, lightheadedness (especially after the first dose), and tiredness. Losartan is less likely than ACE inhibitors to cause a dry cough, but it can still happen. Serious problems include high potassium (which can cause abnormal heart rhythms) and kidney issues.

Avoid using losartan in pregnancy — it can harm the fetus. Also avoid combining it with ACE inhibitors or aliskiren unless a specialist recommends it. Watch interactions: NSAIDs (ibuprofen, naproxen) can reduce losartan’s effect and raise the risk of kidney injury. Potassium supplements, salt substitutes with potassium, and some potassium-sparing diuretics can lead to dangerously high potassium. Lithium levels can rise if you take losartan with lithium.

If you feel faint, have persistent dizziness, severe belly pain, swelling, or very low urine output, call your doctor. If you notice unusual heartbeats, fainting, or severe breathing problems, seek emergency care.

Buying losartan online? Only use licensed pharmacies that require a prescription. Look for a real address, pharmacist contact, and clear privacy and return policies. Avoid sites that sell prescription meds without a prescription or offer suspiciously low prices. If you want to save money, ask your prescriber about generics, patient assistance programs, or pharmacy discount cards.

Final tip: keep a list of all meds and supplements you take and bring it to appointments. That helps your prescriber spot interactions and pick the safest dose for you. If you’re unsure about any side effect or interaction, ask your doctor or pharmacist — they can give advice tailored to your health and other medications.