Losartan (Cozaar) belongs to a group of drugs called angiotensin II receptor antagonists. It keeps blood vessels from narrowing, which lowers blood pressure and improves blood flow.
Losartan is used to treat high blood pressure (hypertension). It is also used to lower the risk of stroke in certain people with heart disease.
Losartan is used to slow long-term kidney damage in people with type 2 diabetes who also have high blood pressure.
Losartan may also be used for purposes not listed in this medication guide.
Important information
Do not use if you are pregnant. Stop using and tell your doctor right away if you become pregnant. Losartan can cause injury or death to the unborn baby if you take the medicine during your second or third trimester. Use effective birth control.
You should not use this medication if you are allergic to losartan.
If you have diabetes, do not use losartan together with any medication that contains aliskiren (Amturnide, Tekturna, Tekamlo, Valturna).
In rare cases, losartan can cause a condition that results in the breakdown of skeletal muscle tissue, leading to kidney failure. Call your doctor right away if you have unexplained muscle pain, tenderness, or weakness especially if you also have fever, unusual tiredness, and dark colored urine.
Before taking this medicine
You should not use losartan if you are allergic to it.
If you have diabetes, do not use losartan together with any medication that contains aliskiren (Amturnide, Tekturna, Tekamlo, Valturna). You may also need to avoid taking this medicine with aliskiren if you have kidney disease.
To make sure losartan is safe for you, tell your doctor if you have:
FDA pregnancy category D. Do not use if you are pregnant. Stop using and tell your doctor right away if you become pregnant. Losartan can cause injury or death to the unborn baby if you take the medicine during your second or third trimester. Use effective birth control.
See also: Pregnancy and breastfeeding warnings (in more detail)
It is not known whether losartan passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.
How should I take losartan?
Take losartan exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.
You may take losartan with or without food.
Call your doctor if you have ongoing vomiting or diarrhea, or if you are sweating more than usual. You can easily become dehydrated while taking this medication, which can lead to severely low blood pressure or a serious electrolyte imbalance.
Your blood pressure will need to be checked often. Visit your doctor regularly.
It may take 3 to 6 weeks of using losartan before your blood pressure is under control. For best results, keep using the medication as directed. Talk with your doctor if your symptoms do not improve after 3 weeks of treatment.
If you are being treated for high blood pressure, keep using this medication even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid?
Drinking alcohol can further lower your blood pressure and may increase certain side effects of losartan.
Do not use potassium supplements or salt substitutes while you are taking this medicine, unless your doctor has told you to.
Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.
Losartan side effects
Get emergency medical help if you have any of these signs of an allergic reaction to losartan: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
In rare cases, losartan can cause a condition that results in the breakdown of skeletal muscle tissue, leading to kidney failure. Call your doctor right away if you have unexplained muscle pain, tenderness, or weakness especially if you also have fever, unusual tiredness, and dark colored urine.
Call your doctor at once if you have:
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a feeling that you might pass out;
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pain or burning when you urinate;
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pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;
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wheezing, chest pain;
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drowsiness, confusion, mood changes, increased thirst, loss of appetite, nausea and vomiting;
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swelling, weight gain, feeling short of breath, urinating less than usual or not at all; or
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high potassium (slow heart rate, weak pulse, muscle weakness, tingly feeling).
Common losartan side effects may include:
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cold or flu symptoms such as stuffy nose, sneezing, sore throat, fever;
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dry cough;
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muscle cramps;
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pain in your legs or back;
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stomach pain, diarrhea;
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headache, dizziness;
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tired feeling; or
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sleep problems (insomnia).
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Losartan dosing information
Usual Adult Dose of Losartan for Diabetic Nephropathy:
Initial dose: 50 mg orally once a day.
Maintenance dose: 25 to 100 mg orally in 1 to 2 divided doses.
Usual Adult Dose for Hypertension:
Initial dose: 50 mg orally once a day.
Maintenance dose: 25 to 100 mg orally in 1 to 2 divided doses.
What other drugs will affect losartan?
Tell your doctor about all medicines you use, and those you start or stop using during your treatment with losartan, especially:
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a diuretic or "water pill";
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other blood pressure medications;
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lithium;
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celecoxib; or
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aspirin or other NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen (Advil, Motrin), naproxen (Aleve), celecoxib, diclofenac, indomethacin, meloxicam, and others.
This list is not complete. Other drugs may interact with losartan, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
