Losartan | Side Effects, Dosage, Uses & More
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Generic Name:

losartan, Oral tablet

All Brands

  • Cozaar
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Highlights for losartan

Oral tablet
1

Losartan is an oral drug that’s used to treat hypertension (high blood pressure). It’s also used to help your kidneys work better if you have diabetes and to reduce your risk of a stroke if you have high blood pressure and the heart condition left ventricular hypertrophy.

2

Your dose will be between 25–100 mg per day. You’ll take losartan by mouth once or twice per day.

3

You shouldn’t take this drug if you’re pregnant or plan to become pregnant. Losartan can harm or be fatal to your unborn baby.

4

Tell your doctor if you have heart failure, a narrowing of the arteries that carry blood to your kidney (renal artery stenosis), or low blood pressure. You may not be able to take this drug.

5

Common side effects include dizziness, stuffy nose, back pain, diarrhea, tiredness, low blood sugar, chest pain, and high or low blood pressure.

IMPORTANT INFORMATION

FDA warning

This drug has a Black Box Warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients to effects that may be dangerous.

Use during pregnancy warning. You shouldn’t take this drug if you’re pregnant or plan to become pregnant. Losartan can harm or be fatal to your unborn baby. If you get pregnant, stop taking this medicine right away and call your doctor.

Active renin-angiotensin system

Tell your doctor if you have heart failure, a narrowing of the arteries that carry blood to your kidneys (renal artery stenosis), or low blood pressure (hypotension). In these conditions, your kidneys depend on the renin-angiotensin system. Taking this drug can also activate this system. If you take losartan when your renin-angiotensin system is activated, you can damage your kidneys.

Low blood pressure (hypotension)

This drug may cause low blood pressure. This may cause you to feel faint or dizzy. If this happens, call your doctor right away and lie down.

What is losartan?

Losartan is a prescription drug. It’s available as an oral tablet.

Losartan is available as a generic drug. Generic drugs usually cost less. In some cases they may not be available in every strength or form as the brand. Talk to your healthcare provider to see if the generic will work for you.

Losartan may be taken as part of a combination therapy with other medications to lower your blood pressure.

Why it's used

Losartan is used to treat high blood pressure and to reduce your risk of a stroke if you have high blood pressure and the heart condition left ventricular hypertrophy. This drug is also used to treat diabetic nephropathy. This will help your kidneys work better if you have diabetes.

How it works

Losartan belongs to a class of drugs called angiotensin receptor blockers. A class of drugs is a group of medications that work in a similar way. They are often used to treat similar conditions.

More Details

How it works

Losartan belongs to a class of drugs called angiotensin receptor blockers. A class of drugs is a group of medications that work in a similar way. They are often used to treat similar conditions.

Losartan works by blocking the action of angiotensin II, a chemical in your body that causes your blood vessels to tighten and narrow. This drug helps to relax and widen your blood vessels. This lowers your blood pressure.

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losartan Side Effects

Oral tablet

More Common Side Effects

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

The most common side effects that occur with losartan include:

  • upper respiratory infections, such as the common cold

  • dizziness

  • stuffy nose

  • back pain

  • diarrhea

  • tiredness

  • low blood sugar

  • chest pain

  • high or low blood pressure

Serious Side Effects

Call your doctor right away if you have any of these serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency.

  • high potassium blood levels. Symptoms include:

    • heart rhythm problems
    • muscle weakness
    • slow heart rate
  • allergic reactions. Symptoms include:

    • swelling of your face, lips, throat or tongue
  • low blood pressure (hypotension). Symptoms include:

    • feeling faint or dizzy
  • kidney disease. If you already have kidney problems, this drug may make your kidney function worse. Symptoms include:

    • swelling in your feet, ankles, or hands
    • unexplained weight gain
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Losartan does not cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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losartan May Interact with Other Medications

Oral tablet

Losartan can interact with other medications, herbs, or vitamins you might be taking. An interaction is when a substance changes the way a drug works. This can be harmful or cause the drugs that you take to not work as well. To help prevent interactions, your doctor should manage all of your medications carefully. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Alcohol interaction

Using drinks that contain alcohol while taking this drug can cause a sedative effect. You may have slowed reflexes, poor judgment, and sleepiness. This can be dangerous.

Medications that might interact with this drug

Bipolar disorder drugs

Losartan may increase the levels of bipolar disorder drugs in your body. This can cause toxicity.

These drugs include:

  • lithium

Blood pressure drugs

Taking other medicines that lower your blood pressure and work on your renin-angiotensin system with losartan has risks. Taking these drugs together can increase your risk of high blood potassium levels, kidney damage, and low blood pressure (hypotension).

These drugs include:

  • aliskiren

Non-steroidal anti-inflammatory drugs (NSAIDs)

Using losartan with NSAIDs can increase your risk of kidney damage. Your risk may be higher if you have poor kidney function, are a senior, take a water pill, or are dehydrated. NSAIDs may also reduce the blood pressure-lowering effects of losartan. This means that it may not work as well.

These drugs include:

  • naproxen
  • ibuprofen

Tuberculosis drugs

These drugs can increase how fast losartan is removed from your body. This means that it may not work as well to lower your blood pressure.

These drugs include:

  • rifampin

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Losartan warnings
active renin-angiotensin system
People with an active renin-angiotensin system

Tell your doctor if you have heart failure, a narrowing of the arteries that carry blood to your kidneys (renal artery stenosis), or low blood pressure (hypotension). In these conditions, your kidneys depend on the renin-angiotensin system. Taking this drug can also activate this system. If you take losartan when your renin-angiotensin system is activated, you can damage your kidneys.

pregnant women
Pregnant women

Losartan is a category D pregnancy drug. That means two things:

  1. Studies show a risk of adverse effects to the fetus when the mother takes the drug.
  2. The benefits of taking the drug during pregnancy may outweigh the potential risks in certain cases.

This drug can harm or be fatal to your unborn baby.

Tell your doctor if you’re pregnant or plan to become pregnant. Losartan should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

breastfeeding
Women who are breast-feeding

It isn’t known if losartan passes into breast milk. If it does, it may cause side effects in a child who is breast-fed.

Talk to your doctor if you breast-feed your baby. You may need to decide whether to stop breast-feeding or stop taking this medication.

for seniors
For seniors

Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal. If you’re a senior, you may need a lower dose or a different schedule.

for children
For children

This medicine has been studied in children, but it shouldn’t be used in children younger than 6 years.

allergies
Allergies

Losartan can cause a severe allergic reaction. Symptoms include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

Don’t take this drug again if you’ve ever had an allergic reaction to it before. Taking it a second time after an allergic reaction could be fatal.

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How to Take losartan (Dosage)

Oral tablet

All possible dosages and forms may not be included here. Your doctor will tell you what dosage is right for you. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Hypertension

Brand: Cozaar

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg

Generic: losartan

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg
Adult dosage (ages 18–64 years)

Doses range between 25–100 mg per day. You’ll take losartan by mouth once or twice per day.

Child dosage (ages 6–17 years)

The dose is based on your child’s weight. The usual dose is around 0.7 mg/kg of body weight taken once per day. Your child’s doctor will increase or decrease the dose depending on their response to the medication.

Child dosage (ages 0–5 years)

This drug shouldn’t be used in children younger than 6 years.

Senior dosage (ages 65 years and older)

There are no specific recommendations for senior dosing. Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

Diabetic nephropathy

Brand: Cozaar

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg

Generic: losartan

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg
Adult dosage (ages 18–64 years)

Doses range between 25–100 mg per day. You’ll take losartan by mouth once or twice per day.

Child dosage (ages 6–17 years)

The dose is based on your child’s weight. The usual dose is around 0.7 mg/kg of body weight taken once per day. Your child’s doctor will increase or decrease the dose depending on their response to the medication.

Child dosage (ages 0–5 years)

This drug shouldn’t be used in children younger than 6 years.

Senior dosage (ages 65 years and older)

There are no specific recommendations for senior dosing. Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

Reduce the risk of stroke in people with hypertension and left ventricular hypertrophy

Brand: Cozaar

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg

Generic: losartan

Form: Oral tablet
Strengths: 25 mg, 50 mg, and 100 mg
Adult dosage (ages 18–64 years)

50 mg taken by mouth once daily. Your doctor may increase your dose to 100 mg per day if needed.

Child dosage (ages 0–17 years)

This drug shouldn’t be used in children younger than 17 years.

Senior dosage (ages 65 years and older)

There are no specific recommendations for senior dosing. Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Losartan comes with serious risks if you don't take it as prescribed.

If you don't take it at all

Losartan reduces high blood pressure. If you don’t take it, your blood pressure will stay high. This will increase your chance of having a stroke or heart attack.

If you stop taking it suddenly

Don’t stop taking losartan without talking to your doctor. Stopping it suddenly can cause your blood pressure to spike. This may increase your chance for a heart attack or stroke.

If you don't take it on schedule

Your blood pressure may not improve or may get worse. You may have a higher chance of a heart attack or stroke.

What to do if you miss a dose

If you forget to take your dose, take it as soon as you remember. If it’s just a few hours until the time for your next dose, then wait and only take one dose at that time.

Never try to catch up by taking two doses at once. This could result in toxic side effects.

If you take too much

If you take too much of your losartan, you might have these symptoms:

  • feeling like your heart is pounding
  • weakness
  • dizziness

If you think that you’ve taken too much losartan, call your doctor or go to the emergency room right away.

How to tell this drug is working

You may be able to tell that this drug is working if your blood pressure is lower. Your doctor will monitor your blood pressure at your checkups. You can also check your blood pressure at home. Keep a log with the date, time of day, and your blood pressure readings. Bring this diary with you to your doctor appointments.

You might not be able to tell if this drug is helping your kidney function. However, you should keep taking it to stop your kidneys from getting more damaged. 

You might not be able to tell if this drug is working to reduce your risk of stroke. However, you should keep taking this drug unless your doctor tells you to stop.

Losartan is used for long-term treatment.

Store losartan at room temperature

  • Keep it from 59°F (15°C) to 86°F (30°C).
  • Don’t freeze this drug.
  • Keep it away from light.
  • Keep it away from high temperature.
  • Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Travel

When traveling with your medication:

  • Always carry it with you or in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport security staff the pharmacy prescription label for your medication. Always carry the original prescription-labeled box with you.

Self-management

You may need to check your blood pressure at home. To do this, you may need to purchase a home blood pressure monitor. You should keep a log with the date, time of day, and your blood pressure readings. Bring this diary with you to your doctor appointments.

Clinical monitoring

During treatment with losartan, your doctor may check your:

  • blood cell levels
  • potassium levels
  • kidney function
  • blood pressure

Hidden costs

You may need to purchase a blood pressure monitor to check your blood pressure at home. These are available at most pharmacies.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other options that may work for you.

What does the pill look like?

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How Much Does losartan Cost?

Oral tablet

We've partnered with GoodRx so you can compare prices, find discounts and save up to 80% on your next prescription. Check out the low coupon prices below — no insurance required.

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Lowest price for losartan

Walmart $8.45
Target (CVS) $9.55
Kroger Pharmacy $9.65
These prices represent the lowest priced national pharmacies for losartan on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for losartan on GoodRx. They may be lower than your insurance.

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on September 25, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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