Losartan and Hydrochlorothiazide

Treats high blood pressure and reduces the chance of strokes. Avoid using salt substitutes containing potassium while taking this medication.

Losartan and Hydrochlorothiazide Overview

Reviewed: July 27, 2015

Losartan and hydrochlorothiazide is a prescription medication used to treat high blood pressure. It is also used to reduce the risk of stroke in patients with high blood pressure and left ventricular hypertrophy.

It is a single product containing 2 medications: losartan and hydrochlorothiazide. Losartan is in a class of medications called angiotensin II receptor antagonists. It works by blocking the action of certain natural substances that tighten blood vessels, allowing the blood to flow more smoothly and the heart to pump more efficiently. Hydrochlorothiazide is in a class of medications called diuretics, or "water pills." It works by causing the kidneys to get rid of unneeded water and salt from the body into the urine.

This medication comes in tablet form and is taken up to twice a day with or without food.

Common side effects of losartan and hydrochlorothiazide include upper respiratory infection, back pain, and rash. It can also cause dizziness. Do not drive or operate heavy machinery until you know how losartan and hydrochlorothiazide affects you.

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Losartan and Hydrochlorothiazide Cautionary Labels


Uses of Losartan and Hydrochlorothiazide

Losartan and hydrochlorothiazide is a prescription medication used to treat high blood pressure. It is also used to reduce the risk of stroke in patients with high blood pressure and left ventricular hypertrophy, but there is evidence that this benefit does not apply to African American patients.

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

Losartan and Hydrochlorothiazide Brand Names

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

Losartan and Hydrochlorothiazide Drug Class

Losartan and Hydrochlorothiazide is part of the drug class:

Side Effects of Losartan and Hydrochlorothiazide

Serious side effects have been reported with losartan and hydrochlorothiazide.  See the "Losartan and hydrochlorothiazide Precautions" section.

Common side effects of losartan and hydrochlorothiazide include the following:

  • upper respiratory infection
  • dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. This is more common when you first start taking losartan and hydrochlorothiazide. To help avoid this problem, get out of bed slowly, resting your feet on the floor for a few minutes before standing up.
  • stuffy nose
  • back pain
  • fast or irregular heartbeat (palpitations)
  • rash

This is not a complete list of losartan and hydrochlorothiazide side effects. Ask your doctor or pharmacist for more information. Tell your doctor if you have a side effect that bothers you or that does not go away. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Losartan and Hydrochlorothiazide Interactions

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

  • potassium supplements
  • salt substitutes containing potassium
  • water pills (diuretics)
  • lithium (a medication used to treat a certain kind of depression)
  • medicines used to treat pain and arthritis, called non-steroidal anti-inflammatory drugs (NSAIDs), including COX-2 inhibitors
  • other medicines to reduce blood pressure

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

Losartan and Hydrochlorothiazide Precautions

Serious side effects have been reported with losartan and hydrochlorothiazide including the following:

  • Injury or death of unborn babies
  • 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 and hydrochlorothiazide.
  • 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.  
  • A new or worsening condition called systemic lupus erythematosus.
  • If you 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.
  • If you have liver problems, you may see a worsening in how well your liver works. Call your doctor if you get nausea, pain in the right upper stomach area (abdomen), yellow eyes or skin (which can be itchy).
  • Eye problems. One of the medicines in losartan and hydrochlorothiazide can cause eye problems that, if left untreated, may lead to vision loss.  Symptoms of eye problems can happen within hours to weeks of starting losartan and hydrochlorothiazide. Tell your doctor right away if you have:
    • decrease in vision
    • eye pain

Do not take losartan and hydrochlorothiazide if you:

  • are allergic to losartan and hydrochlorothiazide or to any of its ingredients
  • are allergic to any sulfonamide-containing medicines ("sulfa"). Ask your doctor if you are not sure what "sulfa" medicines are
  • are not passing urine
  • have diabetes and are taking a medicine called aliskiren to reduce blood pressure

Losartan and Hydrochlorothiazide Food Interactions

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of losartan and hydrochlorothiazide, salt substitutes containing potassium should be avoided.  

Inform MD

Before taking losartan and hydrochlorothiazide, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • are allergic to losartan and hydrochlorothiazide or to any of its ingredients
  • are pregnant or planning to become pregnant
  • are breastfeeding or plan to breastfeed. Losartan and hydrochlorothiazide can pass into your milk and may harm your baby. You and your doctor should decide if you will take losartan and hydrochlorothiazide or breastfeed. You should not do both.
  • have been vomiting, having diarrhea, sweating a lot, or not drinking enough fluids. These could cause you to have low blood pressure
  • have liver problems
  • have kidney problems
  • have systemic lupus erythematosus
  • have diabetes
  • have asthma
  • have gout
  • have any allergies

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

Losartan and Hydrochlorothiazide and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant. The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Losartan and hydrochlorothiazide falls into category D. It has been shown that use of losartan and hydrochlorothiazide in pregnant women caused some babies to be born with problems. However, in some serious situations, the benefit of using this medication may be greater than the risk of harm to the baby.

Losartan and Hydrochlorothiazide and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is unknown whether losartan is excreted in human milk, but significant levels of losartan and its active metabolite were shown to be present in rat milk. Hydrochlorothiazide appears in human milk. Because of the potential for adverse effects on the nursing infant, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Losartan and Hydrochlorothiazide Usage

Take losartan and hydrochlorothiazide exactly as prescribed.

Losartan and hydrochlorothiazide comes in tablet form and is taken up to twice a day, with or without food. If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of losartan and hydrochlorothiazide at the same time.

Losartan and Hydrochlorothiazide Dosage

Take this medication exactly as prescribed by your doctor.  Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

  • the condition being treated
  • other medical conditions you have
  • other medications you are taking
  • how you respond to this medication
  • your weight
  • your height
  • your age
  • your gender

Dosing must be individualized. The usual starting dose of losartan is 50mg once daily, with 25mg recommended for patients with intravascular volume depletion and patients with a history of hepatic impairment. Losartan can be administered once or twice daily at total daily doses of 25 to 100mg. Hydrochlorothiazide is effective in doses of 12.5mg to 50mg once daily and can be given at doses of 12.5 to 25mg as losartan and hydrochlorothiazide.

The usual dose of losartan and hydrochlorothiazide is one tablet of losartan and hydrochlorothiazide 50/12.5 once daily. More than two tablets of losartan and hydrochlorothiazide 50/12.5 once daily or more than one tablet of losartan and hydrochlorothiazide 100/25 once daily is not recommended. The maximal antihypertensive effect is attained about 3 weeks after initiation of therapy.

Losartan and Hydrochlorothiazide Overdose

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

If losartan and hydrochlorothiazide is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur.  However, if overdose is suspected, seek emergency medical attention.

Other Requirements

Store losartan and hydrochlorothiazide at room temperature in a tightly closed container, and keep out of the light. Keep this and all medicines out of the reach of children.

Do not use losartan and hydrochlorothiazide for a condition for which it was not prescribed. Do not give losartan and hydrochlorothiazide to other people, even if they have the same symptoms that you have. It may harm them.

Losartan and Hydrochlorothiazide FDA Warning

Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When pregnancy is detected, discontinue losartan and hydrochlorothiazide as soon as possible. These adverse outcomes are usually associated with the use of these drugs in the second and third trimester of pregnancy. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents. Appropriate management of maternal hypertension during pregnancy is important to optimize outcomes for both mother and fetus.

In the unusual case that there is no appropriate alternative to therapy with drugs affecting the renin-angiotensin system for a particular patient, apprise the mother of the potential risk to the fetus. Perform serial ultrasound examinations to assess the intra-amniotic environment.

If oligohydramnios is observed, discontinue losartan and hydrochlorothiazide, unless it is considered life-saving for the mother. Fetal testing may be appropriate, based on the week of pregnancy. Patients and physicians should be aware, however, that oligohydramnios may not appear until after the fetus has sustained irreversible injury.

Thiazides cross the placental barrier and appear in cord blood. There is a risk of fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions that have occurred in adults.