Losartan
Tablet
Quick Summary
Losartan blocks the hormone angiotensin II, relaxing blood vessels and lowering blood pressure. It rarely causes the dry cough seen with ACE inhibitors.
Medical Uses
How it's taken
Usually taken once or twice a day at the same times each day.
Keep taking it even if you feel well, and don't stop suddenly without talking to your doctor.
Your doctor decides the right dose for you and how long to take it.
Your doctor decides the right dose for you. Follow their instructions and the label.
Common Side Effects
Dizziness
Especially at first.
Tiredness
Sometimes.
Raised potassium
Checked by blood tests.
Interactions
Potassium supplements
Can raise potassium too much.
Anti-inflammatory painkillers
Such as ibuprofen can reduce the effect and affect the kidneys.
Lithium
Levels can rise.
Critical Warnings
Not in pregnancy
Black Box Warning: Can harm an unborn baby; tell your doctor if you're pregnant or planning to be.
Kidney checks
Blood tests check kidney function and potassium.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Losartan: drug information(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Losartan: medicine for high blood pressure(opens in a new tab) · NHS