Losartan potassium is a generic medication that’s prescribed to treat high blood pressure (hypertension). It’s also approved to treat kidney disease and lower the risk of stroke in some people with high blood pressure.
Losartan belongs to a group of drugs known as angiotensin II receptor blockers (ARBs). You can find it in the United States under the brand name Cozaar.
Losartan is available by prescription only. It comes in the form of an oral tablet that you take by mouth.
How does losartan work?
Blood pressure is the force of your blood as it pushes against your blood vessels. The narrower the vessel, the higher the pressure against its walls. When your blood pressure remains high, those blood vessels can become less flexible over time. This can raise your risk of complications, like a heart attack or stroke.
Losartan works by blocking angiotensin II. This enzyme in your body causes your blood vessels to narrow. When angiotensin II is blocked, it reduces the enzyme’s ability to tighten or constrict your blood vessels. Losartan and other ARB medications help relax blood vessels, which in turn, helps lower your blood pressure.
A lower blood pressure can help increase the supply of blood and oxygen to your heart.
Standard or optimum blood pressure for adults is 120/80, measured in millimeters of mercury (mmHg). Your healthcare professional may recommend losartan if your blood pressure is consistently above 130/80, which they consider as stage 1 hypertension. They may also prescribe it to:
- lower the risk of a stroke if you have high blood pressure or an enlarged heart
- treat kidney problems if you have type 2 diabetes and high blood pressure
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How quickly does losartan lower blood pressure?
You may notice that your blood pressure is lowered during the first few hours after you take losartan. But it may take up to 6 weeks to experience the medication’s full effects.
If your blood pressure doesn’t reach the target level (usually 120/80 or under) after 6 weeks, your doctor may increase your dose or add other medications to your plan. It is also possible that your doctor may replace losartan with another blood pressure medication.
How much does losartan lower blood pressure?
Recent evidence on how much blood pressure is lowered with losartan is limited.
A 1995 study of non-Black adult men and women with mild hypertension notes that, within a 24-hour period, all doses of losartan:
- lowered the mean systolic blood pressure (the top number) between 9.4 and 14.2 mmHg
- lowered the mean diastolic blood pressure (the bottom number) between 5.6 and 9.0 mmHg
A 2002 study involving 308 adults with high systolic blood pressure (140 to 200 mmHg) also noted that taking losartan once per day reduced the readings between 8.4 and 14.8 mmHg over 12 weeks of treatment.
Larger and more comprehensive research is needed to determine how much losartan may lower blood pressure in different populations and for other diagnoses.
Is there anything to avoid when you take losartan?
Losartan can interact with some other medications. That’s why it’s important to talk with your healthcare team about any medications, over-the-counter drugs, and supplements that you’re taking.
To avoid possible interactions, your doctor may want you to avoid or limit the following drugs when you take losartan:
- medications or supplements that increase your potassium levels, such as potassium chloride, and some diuretics (water pills) like spironolactone (Aldactone) and eplerenone (Inspra)
- lithium, which is often prescribed to treat bipolar disorder and mental health conditions
- nonsteroidal anti-inflammatory drugs, such as ibuprofen, naproxen, and aspirin
- some other medications that help lower blood pressure, such as angiotensin converting enzyme inhibitors like enalapril (Vasotec), ramipril (Altace), lisinopril (Zestril), and benazepril (Lotensin), in addition to the blood pressure drug aliskiren (Tekturma)
It’s also important to not take losartan if you’re pregnant, as it may cause injury and death to the fetus.
How to take losartan
Losartan and Cozaar come as tablets that you swallow. Usually, you take losartan once or twice per day, depending on your symptoms. If you take it once per day, your healthcare professional may recommend you do so at night.
You may start on a low dose of 25 or 50 milligrams (mg) per day. Then, your healthcare professional may increase the dose as needed. The maximum daily losartan dose you can take is 100 mg.
Your initial and maintenance dose may depend on what you take losartan for.
What are the most common side effects of losartan?
Losartan may not cause as many side effects as other blood pressure medications. Still, some side effects are possible. The most common side effects of losartan include:
- dizziness
- upper respiratory infections
- stuffy nose
- back pain
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Get free cardCan losartan cure high blood pressure?
No medication “cures” high blood pressure. But drugs such as losartan may help you manage it and reduce the chance of complications.
Besides pharmaceutical treatment, your healthcare professional may also recommend you consider lifestyle strategies, including:
- weight management
- reduced salt intake
- nutrient-dense diets
- regular physical activity
Alternative medications to losartan
If losartan isn’t working well to lower your blood pressure, your doctor or healthcare professional may switch you to one or more of these medications:
- Other angiotensin II receptor blockers: candesartan (Atacand) and irbesartan (Avapro)
- Beta-blockers: acebutolol (Sectral) and nadolol (Corgard)
- Calcium channel blockers: amlodipine (Norvasc) and verapamil (Verelan)
- Angiotensin converting enzyme inhibitors: benazepril (Lotensin) and captopril (Capoten)
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Summary
Losartan works by blocking the action of an enzyme in your body that tightens and narrows your blood vessels. By blocking this enzyme, losartan can help your blood vessels relax. This, in turn, can help lower your blood pressure.
Although losartan starts having an effect as soon as you take it, it could take up to 6 weeks to notice its full effects. If your blood pressure doesn’t improve within this timeframe, or you have bothersome side effects, let your doctor know. They can look into other drugs that may be a better option for you.