Medically reviewed by Drugs.com. Last updated on Mar 7, 2022.
When pregnancy is detected, discontinue losartan as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury or death to the developing fetus .
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Cardiovascular Agent
Pharmacologic Class: Angiotensin II Receptor Antagonist
Uses for losartan
Losartan is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. Lowering blood pressure may reduce the risk of strokes and heart attacks.
Losartan is an angiotensin II receptor blocker (ARB). It works by blocking a substance in the body that causes blood vessels to tighten. As a result, losartan relaxes the blood vessels. A lower blood pressure will increase the supply of the blood and oxygen to the heart.
Losartan is also used to decrease the risk of stroke in patients with high blood pressure and enlargement of the heart. It is also used to treat kidney problems in patients with type 2 diabetes and a history of hypertension.
Losartan is available only with your doctor's prescription.
Before using losartan
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For losartan, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to losartan or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of losartan to treat high blood pressure in children 6 years of age and older. However, safety and efficacy have not been established in children younger than 6 years of age.
No information is available on the relationship of age to the effects of losartan to treat other indications in the pediatric population. Safety and efficacy have not been established.
Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of losartan combination in the elderly.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking losartan, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using losartan with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using losartan with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Potassium Citrate
- Potassium Phosphate
Using losartan with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Amtolmetin Guacil
- Choline Salicylate
- Flufenamic Acid
- Mefenamic Acid
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Propionic Acid
- Salicylic Acid
- Sodium Salicylate
- Tiaprofenic Acid
- Tolfenamic Acid
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Other medical problems
The presence of other medical problems may affect the use of losartan. Make sure you tell your doctor if you have any other medical problems, especially:
- Angioedema (an allergic reaction) with other blood pressure medicines (eg, benazepril, enalapril, lisinopril, Lotrel®, Vasotec®, Zestoretic®, Zestril®), history of—Use may cause this condition to reoccur.
- Congestive heart failure, severe—Use may lead to kidney problems.
- Diabetic patients who are also taking aliskiren (Tekturna®) or
- Patients with kidney disease who are also taking aliskiren (Tekturna®)—Should not be used in patients with these conditions.
- Electrolyte imbalances (eg, high or low potassium or sodium in the body)—Use with caution. May make these conditions worse.
- Kidney disease or
- Liver disease (including cirrhosis)—Use with caution. The effects may be increased because of slower removal of losartan from the body.
Proper use of losartan
In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and changes in the types of foods you eat, especially foods high in sodium (salt). Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.
Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
Remember that losartan will not cure your high blood pressure but it does help control it. You must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life. If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.
Losartan comes with a patient information insert. Read and follow the instructions carefully. Ask your doctor if you have any questions.
Losartan may be taken with or without food.
If you are unable to swallow tablets, ask your pharmacist about preparing an oral suspension for you.
The dose of losartan will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of losartan. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For high blood pressure:
- Adults—At first, 50 milligrams (mg) once a day. Your doctor may adjust your dose as needed.
- Children 6 to 16 years of age—Dose is based on body weight and must be determined by your doctor. The starting dose is usually 0.7 milligram (mg) per kilogram (kg) of body weight per day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 50 mg per day.
- Children younger than 6 years of age—Use and dose must be determined by your doctor.
- For lowering risk of stroke in patients with high blood pressure and enlargement of the heart:
- Adults—At first, 50 milligrams (mg) once a day. Your doctor may adjust your dose and add another medicine based on your blood pressure response.
- Children—Use and dose must be determined by your doctor.
- For diabetic nephropathy:
- Adults—At first, 50 milligrams (mg) once a day. Your doctor may adjust your dose based on your blood pressure response.
- Children—Use and dose must be determined by your doctor.
- For high blood pressure:
If you miss a dose of losartan, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using losartan
It is very important that your doctor check your progress at regular visits to make sure that losartan is working properly. Blood and urine tests may be needed to check for unwanted effects.
Using losartan while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using losartan, tell your doctor right away.
Dizziness or lightheadedness may occur after the first dose of losartan, especially if you have been taking a diuretic (water pill). Make sure you know how you react to losartan before you drive, use machines, or do anything else that could be dangerous if you are dizzy or not alert.
Check with your doctor right away if you become sick while taking losartan, especially if you have severe or continuing nausea, vomiting, or diarrhea that does not stop. These conditions may cause you to lose too much water and may lead to low blood pressure. You can also lose water by sweating, so drink plenty of water during exercise or in hot weather.
Ask your doctor before you use medicines, supplements, or salt substitutes that contain potassium.
Avoid alcoholic beverages until you have discussed their use with your doctor. Alcohol may make the low blood pressure effect worse or increase the possibility of dizziness or fainting.
Do not take other medicines unless they have been discussed with your doctor. This especially includes prescription or nonprescription (over-the-counter [OTC]) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, and herbal or vitamin supplements.
Losartan side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Blurred vision
- burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- difficult breathing
- dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
- fast or irregular heartbeat
- nausea or vomiting
- numbness or tingling in the hands, feet, or lips
- stomach pain
- unusual tiredness or weakness
- weakness or heaviness of the legs
Incidence not known
- Black, tarry stools
- bleeding gums
- blood in the urine or stools
- decreased urine output
- difficulty swallowing
- hives, itching, skin rash
- increased thirst
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- muscle pain or cramps
- pinpoint red spots on the skin
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- tightness in the chest
- unusual bleeding or bruising
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Body aches or pain
- continuing ringing or buzzing or other unexplained noise in the ears
- decreased interest in sexual intercourse
- difficulty having a bowel movement (stool)
- ear congestion
- feeling of constant movement of self or surroundings
- feeling sad or empty
- headache, severe and throbbing
- hearing loss
- inability to have or keep an erection
- increased sensitivity of the skin to sunlight
- lack of appetite
- loss in sexual ability, desire, drive, or performance
- loss of interest or pleasure
- loss of voice
- redness or other discoloration of the skin
- sensation of spinning
- severe sunburn
- sore throat
- stuffy or runny nose
- trouble concentrating
- trouble sleeping
Incidence not known
- Change or loss of taste
- dark urine
- general tiredness and weakness
- light-colored stools
- yellow eyes and skin
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Frequently asked questions
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