Losartan: what is the right dosage for me?

Medications and dosages aren't really a one-size-fits-all kind of thing. But when it comes to finding the right dosage, it's not always as easy as trying on shoes. Sometimes it can take time and multiple-dose adjustments by your healthcare provider to reach the dosing schedule that's right for you. If you're just starting treatment with losartan or recently had your dosage adjusted, here's what you need to know.

The standard starting dose for adults taking losartan is a 50 mg tablet, taken once a day by mouth. Losartan is approved by the U.S. Food and Drug Administration (FDA) to treat high blood pressure, reduce the risk of stroke in patients with high blood pressure, and manage kidney problems associated with diabetes (diabetic nephropathy) (FDA, 2018). 

The suggested starting dose for the treatment of any of these conditions is the same. Those being treated for high blood pressure with left ventricular hypertrophy may be prescribed losartan as well as a diuretic such as hydrochlorothiazide as an additional treatment (FDA, 2018).

Your healthcare provider may start you on a lower dose if you have certain health conditions. This lower dose is typically 25 mg, taken once daily. Those who may get a lower starting dose of losartan include those with liver problems, older adults, and individuals who are also taking diuretics ("water pills") (FDA, 2018).

If you start on a dosage of 50 mg, you may have your dosage increased if 50 mg of losartan is not enough to adequately lower your blood pressure to within a healthy range. If this is the case, your dosage may be increased from 50 mg to 100 mg, taken once daily. 

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Doses may be increased up to a maximum of 100 mg in adults with high blood pressure or kidney problems caused by diabetes. For those with high blood pressure and left ventricular hypertrophy receiving a diuretic medication as well, your healthcare provider may increase the dosage of both medications if they see fit (FDA, 2018). In some cases, your healthcare provider may recommend that you take the medication twice daily (Szauder, 2015). 

Losartan tablets should be stored at room temperature, out of the reach of children. In the case of a missed dose, the medication should be taken as soon as you remember unless it's almost time for your next dose. If that's the case, simply take the next dose as scheduled. Losartan may be taken with or without food (FDA, 2018).

Losartan belongs to a drug class called angiotensin receptor blockers (ARBs) that also includes the medications valsartan and irbesartan. ARBs are generally used to treat high blood pressure, though they may be used for other conditions too. Losartan is also approved by the U.S. Food and Drug Administration (FDA) to reduce the risk of stroke and reduce the risk of kidney problems in people with diabetes (DailyMed, 2020).

Losartan may also be used off-label after a heart attack to improve symptoms of heart failure in people who have unfavorable reactions to the first-line treatment, ACE inhibitors. Also, ARBs can be used to treat non-diabetic kidney disease (UpToDate, n.d.). Losartan is available both as generic losartan potassium tablets and under the brand name Cozaar. 

ARBs lower blood pressure by blocking the actions of a hormone called angiotensin II that's naturally produced by the body (Burnier, 2001). This hormone causes blood vessels to constrict, and too much of it may lead to high blood pressure over time. These prescription drugs relax the blood vessels, making them wider, and reducing blood pressure (DailyMed, 2020). 

The most common side effects of losartan include dizziness, stuffy nose, back pain, chest pain, diarrhea, high blood potassium levels, low blood pressure, low blood sugar, and tiredness (FDA, 2018). 

Serious side effects are possible with losartan and may include severe allergic reaction—which can present with hives, itching, rash, and trouble breathing dangerously low blood pressure (hypotension), very high blood potassium (hyperkalemia), which can cause heart problems, and changes in kidney function that may include kidney failure (DailyMed, 2020).

Since high blood levels of potassium can be dangerous, you may need to avoid high-potassium foods when taking ARBs. Past research suggests that consuming foods high in potassium may be safe for people with proper kidney function (Malta, 2016). 

But for those taking ARBs such as losartan who already have kidney problems such as chronic kidney disease (CKD) may need to limit high-potassium foods such as potatoes, tomatoes, oranges, and bananas (Han, 2013). Salt substitutes that use potassium chloride and any dietary supplements or multivitamins that contain potassium should also be avoided. 

Your healthcare provider may monitor your serum potassium levels using a simple blood test to determine if you need to be careful about your potassium intake.

Losartan may also cause serious adverse effects when combined with certain medications. Drug interactions may occur if this prescription medicine is mixed with lithium, non-steroidal anti-inflammatory drugs (NSAIDs) (such as ibuprofen and naproxen), ACE inhibitors, and aliskiren, a different type of medication that's also used to lower blood pressure (DailyMed, 2020). 

You should stop taking losartan if you become pregnant as the drug may cause fetal injury or even death if taken during the final six months (second and third trimester) of pregnancy. You should not breastfeed when taking losartan as the medication may pass into the breast milk (FDA, 2018). 

Tell your healthcare provider or pharmacist about what other drugs or supplements you're taking before starting treatment with losartan. If you need to undergo surgery, make sure to tell your healthcare provider about any medications you are taking. The combination of losartan and the medications used for surgical anesthesia may put you at an increased risk of dangerously low blood pressure (hypotension) (Bertrand, 2001).

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

October 23, 2020

Written by

Linnea Zielinski

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.