1. Losartan/hydrochlorothiazide oral tablet is available as a generic drug and a brand-name drug. Brand name: Hyzaar.
  2. Losartan/hydrochlorothiazide only comes as a tablet you take by mouth.
  3. Losartan/hydrochlorothiazide is a combination of two drugs in a single form. It’s used to treat high blood pressure. It’s also used to reduce the risk of stroke in people with high blood pressure and a heart condition called left ventricular hypertrophy.

Losartan/hydrochlorothiazide is a prescription medication. It comes as an oral tablet.

This drug is available as the brand-name drug Hyzaar and 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.

This is a combination of two drugs in a single form. It’s important to know about all the drugs in the combination because each drug may affect you in a different way.

Losartan/hydrochlorothiazide may be used as part of a combination therapy. That means you need to take it with other drugs.

Why it’s used

Losartan/hydrochlorothiazide is used to treat high blood pressure. It’s given when one drug isn’t enough to lower your blood pressure.

This drug is also used to reduce the risk of stroke in people with high blood pressure and a heart condition called left ventricular hypertrophy. The effectiveness of this drug may be related to your race. Ask your healthcare provider for more information about this topic.

This drug will help control your blood pressure, but it won’t cure high blood pressure.

How it works

Losartan/hydrochlorothiazide contains two drugs that belong in different drug classes. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Losartan is a type of drug called an angiotensin II receptor blocker. It blocks the action of angiotensin II, a chemical in your body that causes your blood vessels to tighten and narrow. Losartan helps to relax and widen your blood vessels, which lowers your blood pressure.

Hydrochlorothiazide is a type of drug called a thiazide diuretic. It’s thought that hydrochlorothiazide works to remove excess salt and water from your body. This keeps your heart from working as hard to pump blood, which lowers your blood pressure.

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

For more information on the possible side effects of losartan/hydrochlorothiazide, or tips on how to deal with a troubling side effect, talk with your doctor or pharmacist.

More common side effects

The more common side effects that occur with losartan/hydrochlorothiazide include:

  • upper respiratory infection, such as the common cold
  • dizziness
  • cough
  • back pain

These effects 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.

Serious side effects

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

  • Serious allergic reaction. Symptoms can include:
    • swelling of your face, lips, throat, or tongue
    • trouble breathing
  • Low blood pressure (hypotension). Symptoms can include:
    • dizziness
    • feeling like you’re going to faint
  • Lupus. Symptoms can include:
    • joint pain
    • stiffness
    • weight loss
    • fatigue
    • skin rash
  • Kidney problems. Symptoms can include:
    • swelling of your feet, ankles, or hands
    • weight gain
  • Eye problems. Symptoms can include:
    • trouble seeing
    • eye pain
  • High or low potassium blood levels. Symptoms can include:
    • heart rhythm problems
    • muscle weakness
    • slow heart rate

Losartan/hydrochlorothiazide oral tablet 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.

Below is a list of medications that can interact with this drug. This list does not contain all drugs that may interact with losartan/hydrochlorothiazide.

Before taking losartan/hydrochlorothiazide, be sure to tell your doctor and 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 you avoid potential interactions.

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

Drugs or supplements that contain potassium

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

Examples of drugs that contain potassium include:

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

Lithium

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

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

Nonsteroidal anti-inflammatory drugs (NSAIDs)

Using this drug with NSAIDs raises 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/hydrochlorothiazide. This means that losartan may not work as well.

Examples of NSAIDs include:

  • ibuprofen
  • naproxen

Blood pressure drugs

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

Examples of these drugs include:

  • angiotensin receptor blockers (ARBs), such as:
    • irbesartan
    • candesartan
    • valsartan
  • angiotensin-converting enzyme (ACE) inhibitors, such as:
    • lisinopril
    • fosinopril
    • enalapril
    • aliskiren

Diabetes drugs

Losartan/hydrochlorothiazide can make your blood sugar levels increase. If you’re taking diabetes medications with losartan/hydrochlorothiazide, your doctor may adjust the dosage of your diabetes medications. Examples of diabetes drugs include:

  • insulin
  • glipizide
  • glyburide
  • pioglitazone
  • rosiglitazone
  • acarbose
  • miglitol

Cholesterol-lowering drugs

Taking losartan/hydrochlorothiazide with certain cholesterol-lowering drugs can decrease the amount of losartan/hydrochlorothiazide in your body. This means it may not work as well.

Your doctor may recommend that you take losartan/hydrochlorothiazide at least 4 hours before you take these drugs, or 4 to 6 hours after you take them.

Examples of these cholesterol-lowering drugs include:

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

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

  • the type of the condition you’re using losartan/hydrochlorothiazide to treat
  • your age
  • other medical conditions you may have, such as kidney damage

Typically, your doctor will start you on a low dosage and adjust it over time to reach the dosage that’s right for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to suit your needs.

Drug forms and strengths

Generic: Losartan/hydrochlorothiazide

  • Form: oral tablet
  • Strengths:
    • 50 mg losartan/12.5 mg hydrochlorothiazide
    • 100 mg losartan/12.5 mg hydrochlorothiazide
    • 100 mg losartan/25 mg hydrochlorothiazide

Brand: Hyzaar

  • Form: oral tablet
  • Strengths:
    • 50 mg losartan/12.5 mg hydrochlorothiazide
    • 100 mg losartan/12.5 mg hydrochlorothiazide
    • 100 mg losartan/25 mg hydrochlorothiazide

Dosage for high blood pressure (hypertension)

Adult dosage (ages 18 to 64 years)

The starting dose is 50 mg losartan/12.5 mg hydrochlorothiazide or 100 mg losartan/12.5 mg hydrochlorothiazide, taken once per day.

Your dosage may depend on the dosage of the blood pressure drug you were taking before. If needed, your doctor may increase your dosage up to 100 mg losartan/25 mg hydrochlorothiazide taken once per day.

The maximum dosage is 100 mg losartan/25 mg hydrochlorothiazide taken once per day.

Child dosage (ages 0 to 17 years)

This drug hasn’t been studied in children and shouldn’t be used in people younger than 18 years.

Senior dosage (ages 65 years and older)

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

Dosage for high blood pressure (hypertension) and left ventricular hypertrophy

Adult dosage (ages 18 to 64 years)

The starting dosage is 50 mg losartan/12.5 mg hydrochlorothiazide once daily.

If this doesn’t control your blood pressure enough, your doctor may increase your dosage to 100 mg losartan/12.5 mg hydrochlorothiazide once daily, followed by 100 mg losartan/25 mg hydrochlorothiazide once daily.

Child dosage (ages 0 to 17 years)

This drug hasn’t been studied in children and shouldn’t be used in people younger than 18 years.

Senior dosage (ages 65 years and older)

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

Special dosage considerations

  • For people with kidney disease: You shouldn’t take this drug if your creatinine clearance (CrCl) is less than 30 ml/min.
  • For people with liver disease: You shouldn’t take this drug if you have liver damage. A lower starting dose of losartan is needed for people with liver disease, but the lower dose is not available in this combination drug.

FDA warning: Use during pregnancy

  • 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 about drug effects that may be dangerous.
  • You should not take this drug while pregnant. This drug can harm or end your pregnancy. If you become pregnant, call your doctor and stop taking this drug right away.

Low blood pressure (hypotension)

Using this drug may cause low blood pressure. You’re more likely to have low blood pressure with this drug if you also take diuretics, are on a low-salt diet, have heart problems, or get sick with vomiting or diarrhea. If you have any of these medical problems, your doctor may monitor you closely when you receive your first dose.

Sensitivity reaction

If you have a history of allergies or asthma, you may get a sensitivity reaction when you first start taking this drug. Symptoms include skin rash, hives, shortness of breath or wheezing, itching, and fever.

Eye problems

This drug may cause eye conditions called myopias and glaucoma. If you have trouble seeing or pain in your eyes, call your doctor and stop taking the drug right away.

Allergy warning

This drug can cause a severe allergic reaction. Symptoms include:

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

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

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.

Alcohol interaction warning

Consuming drinks that contain alcohol can increase your risk of dizziness or lightheadedness from losartan/hydrochlorothiazide. If you drink alcohol, talk to your doctor about whether alcohol use is safe for you while you take this drug.

Warnings for people with certain health conditions

For people with a sulfonamide allergy: If you’re allergic to sulfonamides, don’t take this drug. Be sure to tell your doctor about all of your allergies.

For people with kidney disease: You have a higher risk of serious side effects from this drug. If you have kidney disease and no longer make any urine, you shouldn’t take this drug. Your doctor will monitor your kidney function and adjust your medication as needed.

For people with liver disease: If you have liver disease, you shouldn’t take this drug.

For people with lupus: This drug can cause new or worsening lupus symptoms. Call your doctor right away if this occurs.

For people with diabetes: Your doctor may adjust the dosage of your diabetes drugs while you’re taking this drug. They’ll tell you how often to test your blood sugar levels.

For people with glaucoma: This drug may make your glaucoma worse.

Warnings for other groups

For pregnant women: This drug is a pregnancy category D drug. That means two things:

  1. Research in humans has shown adverse effects to the fetus when the mother takes the drug.
  2. This drug should only be used during pregnancy in serious cases where it's needed to treat a dangerous condition in the mother.

Talk to your doctor if you’re pregnant or planning to become pregnant. Ask your doctor to tell you about the specific harm that may be done to the fetus. This drug should only be used if the potential risk to the fetus is acceptable given the drug’s potential benefit.

Call your doctor right away if you become pregnant while taking this drug.

For women who are breastfeeding: It isn’t known if this drug passes into breast milk. If it does, it may cause side effects in a child who is breastfed.

Talk to your doctor if you breastfeed your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

For seniors: Older adults may process drugs more slowly. As a result, a normal adult dosage may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dosage, or a different dosing schedule.

For children: This drug hasn’t been studied in children and shouldn’t be used in people younger than 18 years.

Losartan/hydrochlorothiazide is used for long-term treatment. It comes with serious risks if you don’t take it as prescribed.

If you don’t take it at all: This drug reduces high blood pressure. If this condition isn’t treated, it can lead to stroke, heart attack, heart failure, kidney failure, and vision problems. It can even be fatal.

If you stop taking it suddenly: Don’t stop taking this drug without talking to your doctor. High blood pressure can occur if you stop taking this drug too suddenly. This may increase your chance for a heart attack or stroke. If you need to stop taking this drug, your doctor will slowly decrease your dose.

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 cause dangerous side effects.

If you take too much: If you take too much of this drug, you may have changes in the amount of electrolytes in your blood. Also, you may have symptoms such as:

  • feeling like your heart is pounding
  • weakness
  • dizziness

If you think you’ve taken too much of this drug, call your doctor or seek guidance from the American Association of Poison Control Centers at 800-222-1222 or through their online tool. But if your symptoms are severe, call 911 or go to the nearest emergency room right away.

How to tell this drug is working: Your blood pressure should be 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.

Keep these considerations in mind if your doctor prescribes losartan/hydrochlorothiazide for you.

General

You can cut or crush the tablet.

Storage

  • Store this drug at room temperature close to 77°F (25°C). It may be stored briefly at a temperature between 59°F and 86°F (15°C and 30°C).
  • Don’t freeze this drug. Keep it away from high temperatures.
  • Keep this drug away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport X-ray machines. They won’t damage your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled container with you.
  • Don’t put this medication in your 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. You should keep a log with the date, time of day, and your blood pressure readings. Bring this log with you to your doctor appointments.

Shop for blood pressure monitors.

Clinical monitoring

While you’re being treated with this drug, your doctor will check your blood pressure and do blood tests to monitor the following:

  • liver function
  • kidney function
  • blood sugar
  • blood potassium

Your diet

Your doctor may have you follow a special diet, such as a low-salt or a low-potassium diet. You may need to avoid potassium supplements and salt substitutes that contain potassium.

Hidden costs

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

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

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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.