Losartan (Cozaar) is a generic drug that is prescribed for certain conditions, including high blood pressure. Losartan comes as an oral tablet and belongs to the angiotensin II receptor blocker (ARB) drug class.

  1. Losartan oral tablet is available as a brand-name drug and a generic drug. Brand name: Cozaar.
  2. Losartan comes only as an oral tablet.
  3. Losartan is used to treat hypertension (high blood pressure) in adults and some children. It is also used to help the kidneys work better in people who have type 2 diabetes and a history of high blood pressure. In addition, it is used to reduce the risk of stroke in someone who has high blood pressure and a heart condition called left ventricular hypertrophy.

FDA warnings

This drug has boxed warnings. These are the most serious warnings from the Food and Drug Administration (FDA). Boxed warnings alert doctors and patients about drug effects that may be dangerous.

You should not take this drug if you are pregnant or planning to become pregnant. Losartan can cause fetal harm or end a pregnancy. If you become pregnant, stop taking this medication right away and call your doctor.

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Losartan is a prescription drug. It comes as an oral tablet.

Losartan is available as the brand-name drug Cozaar. It is also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, they may not be available in every strength or form as the brand-name drug.

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

What is losartan used for?

Losartan is used to:

  • treat high blood pressure in adults and some children
  • lower the risk of stroke in adults with high blood pressure and left ventricular hypertrophy, which is a condition that causes the walls in the heart’s left ventricle to thicken
  • treat diabetic nephropathy, which is a kidney disease caused by diabetes, in certain adults with type 2 diabetes and a history of high blood pressure

Losartan drug class

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

Other ARBs include olmesartan (Benicar), valsartan (Diovan), and telmisartan (Micardis). Like losartan, these drugs can be used to treat high blood pressure and other heart problems.

How losartan works

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

This action helps treat high blood pressure as well as the other two conditions losartan is usually prescribed for. High blood pressure and left ventricular hypertrophy increase the risk of stroke, so lower blood pressure reduces that risk.

Lower blood pressure also reduces the risk of kidney damage. This is because high blood pressure raises the risk of kidney damage that is caused by the high blood sugar levels linked with diabetes.

Losartan can cause mild or serious side effects. The following list contains some of the key side effects that may occur while taking losartan. This list does not include all possible side effects.

For more information on the possible side effects of losartan, or tips on how to manage a bothersome side effect, talk with your doctor or pharmacist.

More common side effects

The more common side effects that can occur with losartan include:

These effects may go away within a few days to a couple of weeks. If they are more severe or do not go away, talk with your doctor or pharmacist.

Serious side effects

You should call your doctor right away if you have serious side effects. Call 911 if symptoms feel life threatening or if you think you are having a medical emergency. Serious side effects and their symptoms can include the following:

  • High potassium blood levels. Symptoms can include:
    • heart rhythm problems
    • muscle weakness
    • slow heart rate
  • Allergic reaction. Symptoms can include:
    • swelling of the face, lips, throat, or tongue
  • Severely low blood pressure. Symptoms can include:
    • feeling faint
    • dizziness
  • Kidney disease. Symptoms can include:
    • swelling in the feet, ankles, or hands
    • fatigue
    • dark or bloody urine

Losartan can interact with several other medications. Different interactions can cause different effects. For instance, some can interfere with how well a drug works, while others can cause increased side effects.

This section gives examples of medications that can interact with losartan. Not all drugs that may interact with losartan are included.

Before taking losartan, tell your doctor or pharmacist about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Lithium

Taking losartan with lithium (Lithobid), a drug used to treat bipolar disorder, may increase the levels of lithium in the body. This can increase the risk of dangerous side effects.

If you need to take these drugs together, your doctor may reduce your lithium dosage.

Blood pressure drugs

Taking losartan with other drugs that work in the same way may increase the chance of low blood pressure, high potassium levels in the blood, and kidney damage.

Examples of these drugs include:

Nonsteroidal anti-inflammatory drugs (NSAIDs)

You should not take NSAIDs with losartan. Using losartan with NSAIDs raises the risk of kidney damage. That risk may be higher if you:

  • has impaired kidney function
  • are an older adult
  • take diuretics (water pills)
  • are dehydrated

NSAIDs may also reduce the blood pressure-lowering effects of losartan. This means that losartan may not work as well if you take it with an NSAID.

Examples of NSAIDs include:

  • naproxen (Aleve)
  • ibuprofen (Advil, Motrin)

Rifampin

Taking losartan with rifampin (Rifadin), a drug used to treat tuberculosis, can increase how quickly the body removes losartan. This means losartan may not work as well to lower blood pressure if taken with this drug.

Drugs or supplements that contain potassium

Losartan can increase the levels of a substance called potassium in the blood. Taking losartan with drugs that contain potassium, potassium supplements, or salt substitutes with potassium can increase the risk of high levels of potassium.

Examples of drugs that contain potassium include:

  • potassium chloride (Klor-Con, Klor Con M)
  • potassium gluconate
  • potassium bicarbonate (Klor-Con EF)

Stopping losartan

Do not stop taking losartan without talking with your doctor. Stopping it suddenly can cause blood pressure to increase quickly. This raises the risk of a heart attack or stroke. If you want to stop taking losartan, talk with your doctor. They will slowly taper the dosage so that you can stop using the drug safely.

The losartan dosage your doctor prescribes will depend on several factors. These include:

  • the type and severity of the condition that losartan is being used to treat
  • your age
  • your weight
  • other medical conditions you may have, such as liver damage

The following information describes dosages that are commonly used or recommended. However, be sure to take the exact dosage prescribed by your doctor. They will determine the best dosage to suit your needs.

Drug forms and strengths

Generic: losartan

  • Form: oral tablet
  • Strengths: 25 milligrams (mg), 50 mg, 100 mg

Brand: Cozaar

  • Form: oral tablet
  • Strengths: 25 mg, 50 mg, 100 mg

Dosage for hypertension (high blood pressure)

Adult dosage (ages 18 to 64 years)

The typical starting dosage is 50 mg once daily. Dosages range between 25 and 100 mg per day.

Child dosage (ages 6 to 17 years)

The dosage is based on the child’s weight. The usual dosage is around 0.7 mg per kilogram (kg) of body weight taken once per day. The child’s doctor will increase or decrease the dosage depending on the child’s response to the medication. The maximum recommended dose for children ages 6 years and older is 100 mg.

Child dosage (ages 0 to 5 years)

This drug should not be used in children younger than 6 years.

Older adult dosage (ages 65 years and older)

There are no specific dosage recommendations for older adults. People in this age group may process drugs more slowly. As a result, a typical adult dosage may cause levels of this drug to be higher than usual in the body. An older adult may need a lower dosage or a different dosing schedule.

Dosage for diabetic nephropathy

Adult dosage (ages 18 to 64 years)

The typical starting dosage is 50 mg once daily. Your doctor may increase the dosage to 100 mg per day if needed.

Child dosage (ages 0 to 17 years)

This drug should not be used in people younger than 18 years for this condition.

Older adult dosage (ages 65 years and older)

There are no specific dosage recommendations for older adults. People in this age group may process drugs more slowly. As a result, a typical adult dosage may cause levels of this drug to be higher than usual in the body. An older adult may need a lower dosage or a different dosing schedule.

Dosage to reduce stroke risk in people with high blood pressure and left ventricular hypertrophy

Adult dosage (ages 18 to 64 years)

The typical dosage is 50 mg taken once daily. Your doctor may increase the dosage to 100 mg per day if needed.

Child dosage (ages 0 to 17 years)

This drug should not be used in people younger than 18 years for this condition.

Older adult dosage (ages 65 years and older)

There are no specific dosage recommendations for older adults. People in this age group may process drugs more slowly. As a result, a typical adult dosage may cause levels of this drug to be higher than usual in the body. An older adult may need a lower dosage or a different dosing schedule.

Special dosage considerations

For people with liver problems: If you have mild to moderate liver problems, your doctor may lower the starting dosage to 25 mg per day.

As with all medications, the cost of losartan can vary. The actual price you will pay depends on your insurance plan, your location, and the pharmacy you use.

Drug coupons: You can visit Optum Perks for price estimates of losartan. These estimates are based on the use of Optum Perks coupons. Note: Optum Perks coupons cannot be used with any insurance copays or benefits.

Financial and insurance assistance: If you need financial support to pay for losartan, or if you need help understanding your insurance coverage, help is available.

Consider looking into websites that offer cost resources and information. Two such organizations are:

Losartan oral tablet comes with several warnings.

FDA warning: Use during pregnancy

This drug has a boxed warning. This is the most serious warning from the Food and Drug Administration (FDA). A boxed warning alerts doctors and patients about drug effects that may be dangerous.

Do not take this drug if you are pregnant or planning to become pregnant. Losartan can harm or end a pregnancy. If you become pregnant while taking losartan, stop taking this medication right away and contact your doctor.

Allergy warning

Losartan can cause a severe allergic reaction. Symptoms include:

  • difficulty breathing
  • swelling of the throat or tongue
  • hives

If you develop these symptoms, call 911 or go to the nearest emergency room.

You should not take this drug again if you have ever had an allergic reaction to it. Taking it again could be fatal (cause death).

Alcohol interaction warning

Consuming alcoholic drinks while taking losartan can cause a sedative effect. This means you may have slowed reflexes, impaired judgment, and sleepiness. This effect can be dangerous if you drive or use other machinery.

Alcohol can also increase the blood pressure-lowering effect of losartan. This increases the risk of blood pressure getting too low.

Low blood pressure warning

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

Warnings for people with certain health conditions

For people with kidney problems: This medication can make kidney disease worse. Symptoms of worsening kidney disease include:

  • swelling in the hands, feet, or ankles
  • unexplained weight gain

For people with liver problems: If you have liver problems, your body will not break down losartan as effectively as usual. For this reason, your doctor may lower your starting dosage.

For people with diabetes and taking aliskiren (Tekturna): You should not take losartan if you have diabetes and are taking a drug called aliskiren to reduce blood pressure. Taking both of these drugs can increase the risk of side effects from losartan. Side effects include low blood pressure, high potassium levels in the blood, and kidney damage. If you have diabetes and are taking aliskiren, talk with your doctor before starting losartan.

Warnings for other groups

For pregnant people: This drug can harm or end a pregnancy. You should tell your doctor if you are pregnant or planning to become pregnant. Losartan should be used during pregnancy only if the potential benefit justifies the potential risk.

For people who are breastfeeding: It is not known whether losartan passes into breast milk. If it does, it may cause side effects in a child who is breastfed. If you breastfeed, talk with your doctor. You may need to decide whether to stop breastfeeding or stop taking this medication.

For older adults: Older adults may process drugs more slowly. As a result, a typical adult dosage may cause levels of this drug to be higher than usual in the body. Older adults may need a lower dosage or a different dosing schedule.

For children: This medication should not be used in children younger than 6 years with high blood pressure.

For Black people: Losartan may not work as well for Black people with certain health problems. For more information, talk with your doctor.

Losartan is used for long-term treatment. It comes with serious risks if it is not taken as prescribed.

If you do not take it at all: Losartan lowers high blood pressure. If you do not take it, your blood pressure will stay high. High blood pressure increases the risk of a stroke or heart attack.

If you do not take it on schedule: Your blood pressure may not improve or may get worse. It may increase your risk of a heart attack or stroke.

What to do if you miss a dose: If you forget to take a dose, you should take it as soon as you remember. If it is just a few hours until the time for the next dose, wait and only take one dose at that time. Never try to catch up by taking two doses at once. This could cause dangerous side effects.

If you take too much: If you take too much losartan, you may have symptoms such as:

  • feeling like your heart is pounding
  • weakness
  • dizziness

If you think you have taken too much of this drug, call your doctor or seek guidance from America’s Poison Centers at 800-222-1222 or through its online tool. If symptoms are severe, call 911 or go to the nearest emergency room right away.

How to tell if the drug is working: Your blood pressure should be lower. Your doctor will monitor your blood pressure at each checkup. You can also check your blood pressure at home.

You may not be able to tell whether this drug is helping your kidney function or reducing the risk of stroke. That does not mean the drug is not working. You should keep taking this drug unless your doctor tells you to stop.

You should keep these considerations in mind if your doctor prescribes losartan.

Storage

  • Store losartan at a room temperature of 59°F to 86°F (15°C and 30°C).
  • Do not freeze this drug.
  • Keep this medication away from light.
  • Do not store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. Your doctor will write the number of refills authorized on the prescription.

Travel

When traveling with this medication:

  • Always carry the medication with you. When flying, never put it into a checked bag. Keep it in a carry-on bag.
  • Do not worry about airport X-ray machines. They cannot harm this medication.
  • You may need to show airport staff the pharmacy label for the medication. Consider carrying it in the original prescription-labeled container.
  • Do not put this medication in a car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Self-management

You may need to check your blood pressure at home. To do this, you may need to buy a home blood pressure monitor. You should keep a log with the date, the time of day, and each blood pressure reading. You should bring this log with you to every doctor’s appointment.

Clinical monitoring

During treatment with losartan, your doctor may check your:

  • potassium levels
  • kidney function
  • blood pressure

Hidden costs

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

Are there any alternatives?

There are other drugs available to treat these health conditions. Some may be better suited for you than others. You should talk with your doctor about other options that may work best for you.

Disclaimer: Medical News Today 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 another 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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