Losartan potassium: Uses, effectiveness, warnings, and side effects

Losartan potassium: Uses, effectiveness, warnings, and side effects

Losartan potassium works by relaxing the blood vessels to allow the blood to flow more efficiently, which reduces a person’s blood pressure. The United States Food and Drug Administration (FDA) approved the drug in 1995 to treat hypertension.

The World Health Organization (WHO) include losartan potassium on their list of essential medicines, which catalogs the most effective and safe medications that experts consider necessary in a healthcare system.

People should not use this medication while pregnant.

This article provides an overview of losartan potassium, including its uses, side effects, potential drug interactions, and other warnings.

What is losartan potassium used for?

Losartan potassium is a type of angiotensin receptor blocker (ARB) known by the brand name Cozaar. Doctors prescribe it to treat hypertension and nephropathy, which is damage to the kidneys, in people with type 2 diabetes.

Doctors most commonly prescribe losartan potassium to treat hypertension in adults and children over 6 years of age.

For many people, lifestyle changes, such as diet, exercise, and avoiding smoking and alcohol, are sufficient to reduce blood pressure to healthy levels. Others may need medication to control their blood pressure.

Untreated high blood pressure can have serious health consequences. Reducing high blood pressure protects against some related health conditions, including:

  • heart attack
  • kidney disease
  • stroke

Medications such as losartan potassium are just one aspect of hypertension treatment. Others include lifestyle and dietary changes. Sometimes, individuals will take losartan alongside other medicines, including diuretics, to control their high blood pressure.

People with diabetes may take losartan to protect their kidneys from damage that occurs as the result of the disease, such as diabetic nephropathy.

Dizziness is a common side effect of losartan. This usually affects people who are just beginning treatment, as their bodies are adjusting to the drug.

Other side effects include:

  • upper respiratory infection
  • nasal congestion
  • back pain

To prevent dizziness or associated injuries, doctors advise people to change positions slowly. For example, carefully move from a lying position to a sitting one, and from a seated position to an upright one.

Avoid driving or using heavy machinery while dizzy. See a doctor if dizziness or lightheadedness persists or gets worse.

Most people do not experience serious adverse reactions to losartan potassium.

If serious side effects do occur, seek urgent medical attention. These include:

  • chest pain
  • fainting
  • irregular heartbeat or palpitations
  • muscle weakness
  • unusual changes in the amount of urine output
  • vomiting

Call 911 or go to the nearest emergency department if symptoms of an allergic reaction to the drug occur. Allergy symptoms include:

  • breathing difficulties
  • itching
  • loss of consciousness
  • rash
  • severe dizziness
  • swelling of the face, tongue, or throat

Allergic reactions to losartan are rare.

Losartan potassium, sold as Cozaar, is available in tablet form in three doses:

  • 25 milligrams (mg)
  • 50 mg
  • 100 mg

The dosage of losartan a person will take will depend on several factors. Their doctor will prescribe the necessary dose for their age, weight, condition, and overall health.

General guidelines for losartan potassium dosage are as follows:

  • Hypertension. Typically, people will take 50 mg once a day, although some individuals may require 100 mg daily. A doctor may prescribe other hypertension drugs or diuretics in addition to losartan.
  • Nephropathy in people with type 2 diabetes. People with diabetes typically begin on 50 mg daily, which may increase to 100 mg daily depending on their reaction to the drug.
  • Hypertension in people with left ventricular hypertrophy. The starting dose is usually 50 mg, and this may increase to 100 mg daily.
  • Hypertension in children. Children aged 6 and over may begin on a very low dose. Rarely, they may require up to 50 mg of losartan per day, depending on their blood pressure response.

Always take losartan exactly as a doctor prescribes. Swallow the tablet with a glass of water, with or without food. Take missed doses as soon as possible, but do not take 2 doses close together. Only take one dose at a time.

A losartan overdose that causes severe symptoms requires emergency medical attention. Call 911 right away. For less severe symptoms, call the American Association of Poison Control Centers at 1-800-222-1222.


Losartan potassium is a hypertension treatment. Research suggests that the medication is safe and effective for most people. People may experience mild side effects, such as dizziness, in the early stages of treatment.

People who experience severe or persistent side effects should contact their doctor right away. Seek emergency medical attention for symptoms that affect breathing or cause swelling of the mouth or throat.

To reduce blood pressure and avoid complications, always take losartan according to a doctor’s instructions. Be sure to discuss any concerns about losartan or its effects with a medical professional.

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