Losartan (angiotensin receptor blocker) vs. beta blockers

Losartan is not a beta-blocker. Losartan belongs to a class of medications called angiotensin II receptor blockers, or ARBs, which are used to treat high blood pressure. These are different from beta-blockers, another type of prescription drug sometimes used to lower blood pressure. 

Beta-blockers such as atenolol and metoprolol are approved by the U.S. Food and Drug Administration to treat high blood pressure (hypertension), abnormally fast heart rate (tachycardia), irregular heartbeat (arrhythmia), and congestive heart failure, as well as to reduce the risk of heart attack (Farzam, 2020). They’re mostly used to regulate heart rhythm and help prevent a second heart attack in individuals who have already had one (Kühlkamp, 2002; Freemantle, 1999). 

In general, these medications lower blood pressure by making your heart beat more slowly and with less force by blocking a hormone called adrenaline, which gets released by your body during times of stress (Frishman, 2010). This effect is also why they’re commonly used off-label to treat performance anxiety (Newman, 2013). 

Some beta-blockers act only on the heart, while others also act on the blood vessels, opening them up in order to improve blood flow and lower blood pressure. Despite their ability to lower blood pressure, prescription drugs other than beta-blockers are typically not the first choice for the treatment of high blood pressure in most patients (James, 2014). 

Although beta-blockers may be prescribed on their own, they’re also used in combination with other medications. Past research has found that combining them with another type of blood pressure medicine called ACE-inhibitors may increase their benefit for patients with certain heart conditions (Vantrimpont, 1997).

Like beta-blockers, ARBs are also blood pressure medications, but they lower blood pressure in a different way. ARBs block the action of a different hormone called angiotensin II (Burnier, 2001). Angiotensin II, which is produced naturally by our bodies, causes our blood vessels to constrict and tells our kidneys to retain water, and too much of this hormone may lead to high blood pressure over time. Medications like losartan block the hormone from acting in our bodies in order to lower blood pressure (DailyMed, 2020).

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Losartan belongs to a drug class called angiotensin receptor blockers (ARBs). This prescription medication is approved by the U.S. Food and Drug Administration (FDA) to treat high blood pressure (hypertension), risk of stroke, and kidney problems from diabetes (DailyMed, 2020). It may also be used off-label to help individuals with heart failure who cannot take certain other blood pressure-lowering medications, and it 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. Tablets are available in 25 mg, 50 mg, and 100 mg strengths. 

Common side effects of losartan depend on what condition is being treated. In people with high blood pressure, the most common side effects of losartan include dizziness, stuffy nose, and back pain. In individuals with type 2 diabetes taking losartan to manage kidney problems, the most common side effects are 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—including hives, itching, rash, and trouble breathing—low blood pressure (hypotension), high blood potassium (hyperkalemia), and changes in kidney function that may include kidney failure in some cases (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 high dietary potassium may be safe for people with proper kidney function (Malta, 2016). 

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, however (Han, 2013). Salt substitutes that use potassium chloride and potassium supplements should also be avoided. 

Losartan may also cause serious adverse effects when combined with certain medications. It should not be mixed with lithium, non-steroidal anti-inflammatory drugs (NSAIDs) (such as ibuprofen and naproxen), ACE inhibitors, and aliskiren, another type of medication that’s also used to lower blood pressure (DailyMed, 2020). 

Let your healthcare provider know if you are pregnant or planning to become pregnant. If taken during pregnancy, losartan can cause fetal injury and even death (FDA, 2018). Tell your healthcare provider or pharmacist about any other drugs or supplements you’re taking before starting losartan to make sure that you receive the most accurate healthcare advice. 

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Current version

October 12, 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.