What Is Losartan Potassium?

Published May 9th, 2020 by Bridget Reed
Fact Checked by
Chris Riley
Updated Date: Jul 7th, 2022

The Center for Disease Control (CDC) estimates that about 45 percent of American adults, or 108 million people, currently suffer from high blood pressure, also known as hypertension. High blood pressure is influenced by a number of factors, including diet, activity level, stress, medications, and medical conditions, and doctors generally advise hypertensive patients to make serious lifestyle changes, like eating right and exercising more. Lifestyle changes will be effective in reducing or eliminating high blood pressure for many people, but others might need additional treatment in the form of blood pressure medication to bring their condition under control. Regardless of how patients get their high blood pressure under control, doing so is critical; high blood pressure is known as the “silent killer” because it is the most common cause of cardiovascular disease-related deaths in the United States, and many people are unaware that they have high blood pressure until it is too late. If your doctor has recommended taking losartan potassium in conjunction with making lifestyle changes to control your high blood pressure, here’s what you need to know about the medication.

What Is Losartan Potassium?

Losartan potassium, manufactured under the brand name Cozaar, belongs to a class of prescription drugs called angiotensin II receptor antagonists (ARBS) or angiotensin II receptor blockers. Cozaar was first approved for medical use in the United States by the Food and Drug Administration (FDA) in 1995 and the generic form, losartan potassium, was released in 2010. Losartan potassium is available by prescription only and is sold in both the generic and brand name forms as an antihypertensive drug. 

What Is Losartan Potassium Used to Treat?

Losartan potassium is primarily used to treat high blood pressure and is also used to help protect the kidneys from damage caused by diabetes in patients who also have high blood pressure. The medication can help lower the risk of strokes in patients with an enlarged heart or high blood pressure at risk of heart disease by working to lower blood pressure.  

High Blood Pressure

Blood pressure is measured as the force at which blood pushes against the walls of the blood vessels as the heart beats. It’s important that the blood flows with enough power to reach all of the organs and extremities, but when blood pressure is too high, it can cause problems. Hypertension, or high blood pressure, occurs when the blood pushes too hard against the walls of the blood vessels consistently and for an extended period of time. High blood pressure causes the heart and blood vessels to work at an increased effort level and less efficiently, which means that more effort is required to provide the tissues and organs with the blood they need to function. If high blood pressure is not managed or controlled by lifestyle changes or medication, it can result in a narrowing of the blood vessels by creating microtears in the walls of the arteries. When the blood vessels narrow, blood is further prevented from reaching the different areas of the body, causing blood pressure to rise even more. Although some high blood pressure has a specific cause, such as taking a medication or having a certain medical condition, the majority of high blood pressure cases have no obvious causes and are primarily influenced by lifestyle factors and genetics.  

Diabetic Nephropathy

People with type 1 or type 2 diabetes are at increased risk of developing serious kidney problems; approximately 25 percent of people with diabetes will develop kidney disease. Diabetic nephropathy refers to damage to the kidneys caused by diabetes and high blood pressure, and it affects the ability of the kidneys to remove waste products and extra fluid from the body. Over time, this condition can lead to kidney failure, which is a life-threatening condition requiring dialysis or a kidney transplant. The best ways to prevent diabetic nephropathy are to maintain a healthy lifestyle and carefully manage the treatment of diabetes and high blood pressure. 

How Does Losartan Potassium Work?

Like other angiotensin II receptor antagonists, losartan potassium works by blocking the action of angiotensin II, a chemical that causes the blood vessels to narrow and tighten. Angiotensin II receptor antagonists are effective at lowering blood pressure because when angiotensin II is blocked from absorption, the blood vessels are able to relax and open. 

What Are the Benefits of Losartan Potassium?

Losartan potassium has been around since the 1990s and has developed a reputation as a reliable, effective drug for treating high blood pressure and diabetic nephropathy. Use of losartan potassium has several benefits:

  • Compared to other blood pressure medications, such as atenolol, losartan potassium is more effective in reducing cardiovascular death, stroke, and myocardial infarction.
  • Losartan potassium reduces the risk of new-onset diabetes in patients with high blood pressure who take the medication.
  • Losartan potassium effectively treats high blood pressure 
  • Losartan potassium is available in a generic form and is highly affordable and accessible for most patients.

Are There Any Risks Associated With Losartan Potassium?

Although there are many benefits associated with losartan potassium, as listed above, taking the medication also poses some risks. Always read the drug information before taking a medication. Risks associated with losartan potassium include:

  • Patients with diabetes should not take losartan with medications like Amturnide, Tekturna, Tekamlo, and Valturna that contain aliskiren, as should patients with kidney disease to avoid problematic drug interactions.
  • Pregnant and breastfeeding women should not use losartan potassium due to risk to the unborn child and newborn infant.
  • Patients should tell their doctors if they become sick, especially if they have vomiting or diarrhea that will not stop. Dehydration may occur and can be dangerous, leading to low blood pressure.
  • Patients should not use salt substitutes or potassium supplements to improve potassium levels while taking this medication. 
  • Patients should avoid all use of non-steroidal anti-inflammatory drugs and NSAIDs like naproxen and ibuprofen while taking this medication.
  • Patients with low blood pressure should use caution when taking this medication. 

What Dose of Losartan Potassium Should I Take?

The dose of losartan potassium that your doctor prescribes will vary depending on the condition being treated, your age, overall health, and other medical conditions. Patients taking losartan potassium for high blood pressure will generally have a starting dose of 50 mg taken orally once per day. After the initial dose, a maintenance dose of 25 to 100 mg will be taken orally in 1 or 2 doses. Patients taking losartan potassium for diabetic nephropathy are likely to be prescribed an initial dose of 50 mg orally once per day before switching to a maintenance dose of between 25 to 100 mg taken orally in 1 or 2 doses per day. Overall, be sure to follow the medical advice of your doctor including informing them about any missed doses and storing the medication at room temperature. 

What Are the Side Effects of Losartan Potassium?

Side effects associated with losartan potassium are categorized as either common or less common, and some may require medical attention. Common side effects associated with losartan potassium that usually do not need medical attention include:

  • Body aches or back pain
  • Continuing ringing or buzzing in the ears
  • Constipation
  • The feeling of constant movement of self or surroundings
  • Headache, sometimes severe or throbbing
  • Inability to have or keep an erection
  • Irritability
  • Loss of sex drive
  • Loss of voice
  • Sensation of spinning
  • Sneezing
  • Stuffy or runny nose
  • Trouble sleeping
  • Chills
  • Ear congestion
  • Feeling sad or empty
  • Hearing loss
  • Increased sun sensitivity
  • Lack of appetite
  • Loss of interest or pleasure
  • Redness or other skin discoloration
  • Severe sunburn
  • Sore throat
  • Trouble sleeping

As long as these common side effects are mild, they should go away within a few days or weeks. If side effects persist or allergic reactions occur, talk to your doctor.
Some side effects of losartan potassium do require medical attention. Check with your health care provider immediately if you experience any of the following serious adverse effects while taking losartan potassium:

  • Blurred vision
  • Confusion
  • Dizziness
  • Fainting
  • Nausea or vomiting
  • Numbness or tingling in the hands, feet, or lips
  • Sweating
  • Weakness or heaviness of the legs
  • Burning, crawling, itching, numbness, prickling, tingling feelings, or “pins and needles”
  • Difficulty breathing
  • Dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • Fast heart rate, irregular heartbeat or chest pain
  • Nervousness
  • Stomach pain
  • Unusual tiredness or weakness

Is Losartan Potassium Safe for Women Who Are Pregnant or Breastfeeding?

Losartan potassium is categorized as pregnancy category D by the FDA for all trimesters, meaning that clinical trials and studies in pregnant women have shown that there is a risk to the fetus when taking losartan potassium. Specifically, losartan potassium is associated with fetal death and morbidity when used in the second and third trimester. Mothers who are going to breast-feed should talk to their doctors if taking losartan potassium while breastfeeding, as conclusive research regarding risks medication transfer from breast milk to the infant has not been conducted. 

Who Should Not Take Losartan Potassium?

Women who are pregnant, nursing, or planning to become pregnant should not take losartan potassium due to the risk of injury or death to the unborn baby associated with the medication. Women should use effective birth control while taking losartan potassium. People who are allergic to losartan potassium should not take the medication, nor should people taking medication that contains aliskiren (Amturnide, Tekturna, Tekamlo, Valturna). Patients with kidney disease, liver disease, congestive heart failure, electrolyte imbalances, or a history of dehydration should make sure to give their doctors a complete medical history prior to taking this medication.

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