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Losartan

Brand names: Cozaar

Losartan is an angiotensin receptor blocker (ARB) that lowers blood pressure and protects the kidneys.

Brand namesCozaar
Type of medicineARB (blood pressure medicine)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It blocks a hormone that narrows blood vessels. It works much like ACE inhibitors but rarely causes a cough.

What it's used for

  • High blood pressure
  • Protecting the kidneys in type 2 diabetes
  • Lowering stroke risk in some people with high blood pressure and an enlarged heart

How to take it

  • Take it once or twice a day, with or without food.
  • Keep taking it even if you feel well.
  • Stand up slowly at first.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Dizziness
  • Stuffy nose
  • Back or leg pain
  • Tiredness
Call 911Swelling of the face, lips, or throat, or trouble breathing
Call your provider todayFainting
Call your provider todayMuscle weakness or a slow or irregular heartbeat (possible high potassium)
Call your provider todayPeeing much less than usual

Warnings

  • Do not take during pregnancy; it can harm an unborn baby.
  • Your provider will check potassium and kidney function.

Other medicines, foods, and alcohol

  • Potassium supplements and salt substitutes can raise potassium too high.
  • NSAIDs can weaken its effect and harm the kidneys.
  • Lithium levels can rise.
  • Avoid combining with an ACE inhibitor or aliskiren unless your provider directs it.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Don't take losartan if you are pregnant. Call your provider right away if you become pregnant.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.