In the U.S.—

• Angiotensin II receptor antagonist
• Antihypertensive

Losartan ( loe-SAR-tan) is used to treat high blood pressure (hypertension). High blood pressure adds to the work load 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. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Losartan works by blocking the action of a substance in the body that causes blood vessels to tighten. As a result, losartan relaxes blood vessels. This lowers blood pressure.

Losartan is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (U.S.)

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:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to losartan. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet—Make certain your health care professional knows if you are on any special diet, such as a low-sodium diet.

Pregnancy—Use of losartan during pregnancy, especially during the second and third trimesters (after the first three months) can cause low blood pressure, severe kidney failure, or even death in the newborn. Therefore, it is important that you check with your doctor immediately if you think that you may be pregnant. Be sure that you have discussed this with your doctor before taking this medicine.

Breast-feeding—It is not known whether losartan passes into breast milk. However, losartan passes into the milk of lactating rats.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of losartan in children with use in other age groups.

Older adults—This medicine has been tested in a limited number of patients 65 years of age or older and has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other 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 health care professional know if you are taking any of the following:

• Diuretics (water pills)—Effects on blood pressure may be increased. In addition, some diuretics make the increase in potassium in the blood caused by losartan even greater

• Kidney disease or
• Liver disease—Effects may be increased because of slower removal of losartan from the body

To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.

In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium. 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 this medicine will not cure your high blood pressure but it does help control it. Therefore, 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.

This medicine may be taken with or without food.

Dosing—

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 number of tablets that you take depends on the strength of the medicine.

• For oral dosage form (tablets):
  • For high blood pressure:
    • Adults—25 to 100 milligrams (mg) a day. The dose may be taken once a day or divided into two doses.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, 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.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the medicine from freezing. Do not refrigerate.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Check with your doctor immediately if you think that you may be pregnant. Losartan may cause birth defects or other problems in the baby if taken during pregnancy.

It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.

Dizziness or lightheadedness may occur after the first dose of this medicine, especially if you have been taking a diuretic (water pill). Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy.

Check with your doctor right away if you become sick while taking this medicine, especially with severe or continuing nausea and vomiting or diarrhea. These conditions may cause you to lose too much water and lead to low blood pressure.

Dizziness, lightheadedness, or fainting may also occur if you exercise or if the weather is hot. Heavy sweating can cause loss of too much water and result in low blood pressure. Use extra care during exercise or hot weather.

Avoid alcoholic beverages until you have discussed their use with your doctor. Alcohol may make the low blood pressure effect worse and/or increase the possibility of dizziness or fainting.

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:

• Rare
  • Hoarseness;  swelling of face, mouth, hands, or feet;  trouble in swallowing or breathing (sudden) 
  
  

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common
  • Cough, fever or sore throat;  dizziness  
  
  

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Headache 
  
  

• Less common
  • Back pain;  diarrhea;  fatigue;  nasal congestion 
  
  

• Rare
  • Cough, dry;  leg pain;  muscle cramps or pain;  sinus problems;  trouble in sleeping 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.