Losartan treats high blood pressure. This medication should not be used during pregnancy. Avoid salt substitutes containing potassium.

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Pharmacist Christine Wicke, PharmD overviews the uses and common side effects of Losartan
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Pharmacist Christine Wicke, PharmD overviews the uses and common side effects of Losartan
Pharmacist Christine Wicke, PharmD, BCPS summarizes the uses, common side effects, and warnings for the ARB class of medications

Losartan Overview

Reviewed: April 17, 2013

Losartan is a prescription medication used to treat high blood pressure. It is also used to lower the chance of stroke in patients with high blood pressure and slow the worsening of diabetic kidney disease (nephropathy) in patients with type 2 diabetes who have or had high blood pressure.

Losartan belongs a group of drugs called angiotensin receptor blockers (ARBs), which help lower blood pressure by relaxing blood vessels.

This medication comes in tablet form and is usually taken once or twice daily. It can be taken with or without food.

Common side effects of losartan include stuffy nose, back pain, and dizziness. Do not drive or operate heavy machinery until you know how losartan affects you.



How was your experience with Losartan?

First, a little about yourself

Tell us about yourself in a few words?

What tips would you provide a friend before taking Losartan?

What are you taking Losartan for?

Choose one
  • Other
  • Diabetic Nephropathies
  • Heart Failure
  • Hypertension
  • Ventricular Dysfunction, Left

How long have you been taking it?

Choose one
  • Less than a week
  • A couple weeks
  • A month or so
  • A few months
  • A year or so
  • Two years or more

How well did Losartan work for you?

Did you experience many side effects while taking this drug?

How likely would you be to recommend Losartan to a friend?

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Losartan Cautionary Labels


Uses of Losartan

Losartan is a prescription medicine used:

  • alone or with other blood pressure medicines to lower high blood pressure (hypertension).
  • to lower the chance of stroke in patients with high blood pressure and a heart problem called left ventricular hypertrophy. 
  • to slow the worsening of diabetic kidney disease (nephropathy) in patients with type 2 diabetes who have or had high blood pressure.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Losartan Brand Names

Losartan may be found in some form under the following brand names:

Losartan Drug Class

Losartan is part of the drug class:

Side Effects of Losartan

Losartan may cause serious side effects. See "Drug Precautions" section.

The most common side effects of losartan in people with high blood pressure are:

  • "colds" (upper respiratory infection)
  • dizziness
  • stuffy nose
  • back pain

Tell your doctor if you get any side effect that bothers you or that won’t go away.

This is not a complete list of side effects. For a complete list, ask your doctor or pharmacist.


Losartan Interactions

Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Especially tell your doctor if you take:

  • aspirin and other nonsteroidal anti-inflammatory medications (NSAIDs) such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn)  
  • celecoxib (Celebrex)
  • diuretics ('water pills') including amiloride (Midamor, in Hydroride, in Moduretic), spironolactone (Aldactone, in Aldactazide), and triamterene (Dyrenium, in Dyazide, in Maxzide)
  • fluconazole (Diflucan)
  • lithium (Eskalith CR, Eskalith, Lithobid)
  • phenobarbital
  • potassium supplements
  • salt substitutes
  • rifampin (Rifadin, Rimactane)
  • other medications to reduce blood pressure

This is not a complete list of losartan drug interactions. Ask your doctor or pharmacist for more information.

Losartan Precautions

Do not take losartan if you are pregnant or plan to become pregnant. losartan can harm your unborn baby causing injury and even death. Stop taking losartan if you become pregnant and call your doctor right away. If you plan to become pregnant, talk to your doctor about other treatment options before taking losartan.

Do not take losartan if you are allergic to any of the ingredients in losartan. See "Forms of losartan" section.

Do not take losartan if you have diabetes and are taking a medicine called aliskiren to reduce blood pressure.

Losartan may cause the following side effects that may be serious:

  • Injury or death of unborn babies. See "FDA Warning" section.
  • Allergic reaction. Symptoms of an allergic reaction are swelling of the face, lips, throat or tongue. Get emergency medical help right away and stop taking losartan.
  • Low blood pressure (hypotension). Low blood pressure may cause you to feel faint or dizzy. Lie down if you feel faint or dizzy. Call your doctor right away.
  • For people who already have kidney problems, you may see a worsening in how well your kidneys work. Call your doctor if you get swelling in your feet, ankles, or hands, or unexplained weight gain.

Losartan may cause dizziness. Do not drive or operate heavy machinery until you know how losartan affects you.

Losartan Food Interactions

Grapefruit and grapefruit juice may interact with losartan and lead to potentially dangerous effects. Discuss the use of grapefruit products with your doctor.

Avoid salt substitues containing potassium while taking losartan.

Inform MD

Tell your doctor about all of your medical conditions including if you:

  • are pregnant or planning to become pregnant. (See pregnancy warning.)
  • are breastfeeding. It is not known if losartan passes into your breast milk.
  • are vomiting a lot or having a lot of diarrhea.
  • have liver problems.
  • have kidney problems

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. 

Losartan and Pregnancy

Do not use losartan while you are pregnant (especially in your second or third trimester). Losartan can harm your unborn baby. If you think you have become pregnant while using this medicine, tell your doctor right away. See "FDA Warning".


Losartan and Lactation

Tell your doctor if you are breastfeeding or if you are planning to breastfeed. It is not known if losartan is excreted in human breast milk or if it will harm your baby.


Losartan Usage

Take losartan exactly as prescribed by your doctor. Your doctor may change your dose if needed. Losartan is a tablet that is taken by mouth with or without food. If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and take the next dose at your regular time.

Losartan may lower your blood pressure within a short time of starting treatment but it may take several weeks for it to reach full benefit. Continue taking losartan even if you feel well. 

Do not use salt substitutes containing potassium without talking to your doctor. 

Losartan Dosage

Your doctor will determine the best dose for you. Follow the directions on your prescription label carefully. Your doctor will probably start you on a low dose of losartan and gradually increase your dose. Losartan can be given once or twice daily with total daily doses ranging from 25 mg to 100 mg.


Losartan Overdose

If you take too much losartan call your local Poison Control Center or seek emergency medical attention right away.

Other Requirements

  • Store losartan tablets at 59°F to 86°F (15°C to 30°C).
  • Keep losartan in a tightly closed container that protects the medicine from light.
  • Keep losartan and all medicines out of the reach of children.

Losartan FDA Warning


When used in pregnancy during the second and third trimesters, drugs that act directly on the renin-angiotensin system can cause injury and even death to the developing fetus. When pregnancy is detected, losartan should be discontinued as soon as possible.