Learn About Losartan Side Effects to Manage Hypertension Safely

Losartan Side Effects Losartan Side Effects

Learn about losartan side effects to manage hypertension safely

Blood pressure is the pressure the blood makes to the blood vessel. If this blood force is too much and higher than 130/80 mmHg per the American Heart Association guidelines, it is called high blood pressure (hypertension). Nearly half of the American adults suffer from hypertension, and most don’t know that they have it. (1-2)

High blood pressure can damage the circulatory system over time, so regulating is crucial. Hypertension is a risk factor for heart attack and stroke, leading causes of death in the U.S. Yet, about one in four adults with hypertension has the condition under control. (1-2)

Losartan is a prescription medicine used for hypertension regulation alone or in combination with other blood pressure drugs. It has been shown as a well-tolerated medication, but still, it has possible side effects that each patient should know. (3)

If the doctor has prescribed you losartan, this article will help you to learn about common and serious side effects. Keep reading to find out in which situations you need to call your doctor immediately.

Losartan relaxes blood vessels and lowers the pressure

Before going into details about losartan’s side effects, it is helpful to understand how it works and the other health conditions when losartan can be used.

Losartan belongs to a group of medications named angiotensin II receptor blockers (ARB). It blocks angiotensin II in the body, a substance that tightens and narrows blood vessels. As a result, losartan relaxes blood vessels; blood can easily flow into the bloodstream and supply the body and heart with oxygen. (4)

This mechanism makes losartan effective in other diseases treatment and is used to:

  • Lower the chance of stroke in patients with high blood pressure and a heart problem called left ventricular hypertrophy (LVH). LVH is an enlargement of the heart’s walls of the left chamber, which is the main pumping chamber. High blood pressure is the most common cause of LVH. You should know that losartan may not decrease the risk of stroke in African Americans with these conditions. (3-4)
  • Slow the worsening of diabetic kidney disease (nephropathy) in people with type 2 diabetes who have or had high blood pressure before. Type 2 diabetes happens mainly in adults and can damage the kidney, so the kidney will not work properly. (3-4)

Losartan’s possible side effects

People with high blood pressure need medical treatment to regulate the pressure, and losartan can be an option. Losartan is generally well tolerated and is in use since 1995. In the initial clinical trials, only 2.3% of the patients discontinued the treatment with losartan due to side effects.

Common side effects

However, there are side effects that people with high blood pressure using losartan may experience. The most common side effects with an incidence of over 2 in 100 patients are:

Losartan Side Effects

Losartan Side Effects – Common side effects

  • “Colds” (upper respiratory infection) – 8%;
  • Dizziness – 3%;
  • Stuffy nose – 2%;
  • Back pain – 2%.

It is good to mention that the incidence of these side effects in the treatment group was similar to that of the subjects on placebo (not taking losartan). (3)

You may feel dizzy after the first dose. It could happen when you take losartan with a diuretic. If you experience dizziness, lie down for a while, then sit and wait to feel better. You should avoid driving and operating machines or other tools that can be dangerous. (5)

People with type 2 diabetes and diabetic kidney disease may have the following most common side effects of losartan:

  • Diarrhea;
  • Tiredness;
  • Low blood sugar;
  • Chest pain;
  • High blood potassium;
  • Low blood pressure. (3)

You might have heard about a persistent dry cough associated with other high blood pressure medications (Angiotensin-converting enzyme inhibitors such as enalapril, lisinopril, captopril, and many more). Two double-blind controlled clinical trials assessed the losartan’s effect on the incidence of the cough. Patients previously treated with lisinopril and had coughs were switched to losartan for eight weeks. The incidence of cough in the losartan group was lower than in the Lisinopril group and was comparable with the placebo or hydrochlorothiazide group. (3)

Serious side effects

Some side effects can be serious, bother the patients, or won’t go away. E.g., severe and continuous diarrhea, nausea, and vomiting may cause losing too much water and result in too low blood pressure (hypotension). (5)

Tell your doctor if you get any of the following side effects:

  • Allergic reaction – is if you experience swelling of the face, lips, throat, or tongue. If it happens, you should stop taking the medication and get emergency medical help right away;
  • Low blood pressure – if you feel faint or dizzy, it could be a symptom of hypotension. If you feel so, lie down and call your doctor right away;
  • Worsening of the kidneys happens in people who already have kidney problems – in such cases, you’ll get swelling in your feet, ankles, or hands or gain weight unexpectedly due to water retention. (3)
  • High blood levels of potassium are expressed with heart rhythm problems, muscle weakness, chest pain, nausea, vomiting, or diarrhea. (3, 6)

You may find out about side effects in the patient information inserted in the losartan pack. (3) Ask your doctor or pharmacist for a complete list of side effects.

Warning and precautions

Fetal toxicity – The major warning that the Food and Drug Administration has issued to losartan is fetal toxicity. Drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduce the renal function of the fetus and increase fetal and neonatal morbidity and death. You can find it in the patient information warning for losartan that says:

“When pregnancy is detected, discontinue losartan as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus.” (3)

Hypotension may occur after the beginning of losartan treatment in patients who use high doses of diuretics. It is a result of depleted salt and the volume of liquids. In this case, the doctor will correct volume or salt depletion before losartan treatment begins. (3)

Renal function and potassium levels monitoring – Losartan and diuretics may change renal function, including acute renal failure, or cause hyperkalemia (higher potassium level in the body than normal). Therefore, your doctor will monitor renal function and potassium levels. (3)

Patients with renal artery stenosis, chronic kidney disease, severe congestive heart failure, or volume depletion are at risk of developing acute renal failure if using losartan. If you are one of this group of patients, regularly visit your doctor to monitor renal function. The doctor might discontinue losartan if he identifies a significant decrease in renal function. (3)

If you experience a serious side effect, you or your doctor can report it to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088). (7)

Dosage and administration

Losartan is available in tablets with a strength of 25 mg, 50 mg, and 100 mg.

For hypertension treatment, hypertensive patients with left ventricular hypertrophy, and diabetes nephropathy, the usual adult starting dose is 50 mg once daily. The dose can be increased to 100 mg daily for all indications except hypertension.

In patients with hypertension and left ventricular hypertrophy, losartan can be administered with the diuretic hydrochlorothiazide, which helps the body to get rid of extra salt and water.

In the pediatric population older than six years, the starting dose is 0.7 mg per kg once daily (up to 50 mg).

If you take losartan more than needed, it could lead to hypotension and tachycardia. Dizziness, fainting, or a fast or slow heartbeat are overdose symptoms. In some overdose cases, you might need supportive treatment. Therefore, call the poison control helpline at 1-800-222-1222. You may find available information online at https://www.poisonhelp.org/help. (3, 7)

What you should tell your doctor before taking losartan

Before you start taking losartan, tell your doctor about all of your medical conditions, including:

  • Pregnancy or planning to become pregnant as explained before;
  • Breastfeeding – it is unknown if losartan passes into your breast milk. Therefore, losartan should not be used, or the mother should stop breastfeeding;
  • A lot of vomiting or diarrhea;
  • Having liver problems;
  • Having kidney problems;

All the medication you take, supplements, and vitamins due to possible interaction with losartan or dual activity on blood pressure reduction. (3)

Hypertension management requires blood pressure monitoring and lifestyle changes.

Once you get high blood pressure, it cannot be cured, but you can certainly control it. Regular medical treatment plays an important role; sometimes, it takes time to find the appropriate drug or combination of drugs that works for you.

High blood pressure monitoring at home will give your doctor feedback on how the medication/s work. Regular and proper use of a home blood pressure monitor will tell you if your pressure is in the normal range, elevated, or high. Learn how to properly measure; here are some useful tips:

  • No cigarettes, caffeinated drinks, or exercise 30 minutes before measuring;
  • Get rest 5 minutes before you measure;
  • Sit with a straight back and flat feet on the floor;
  • Put your arm on a flat surface and your upper arm on a heart level;
  • Don’t measure the pressure over clothes;
  • Measure every day at the same time, two to three times, as your doctor advised you;
  • Write the results in a tracker. (2)

This lifetime blood pressure management means making changes that will contribute to the best results. American Heart Association recommends the following:

  • Decrease salt and salty food;
  • Introduce a heart-healthy diet rich in vegetables, fruits, whole grains, fish, nuts, legumes, and other healthy food;
  • Limit food rich in saturated fats, red meat, sweets, and sweetened beverages;
  • Be physically active for at least 150 minutes weekly, with activities that you like;
  • Learn to manage stress;
  • Keep your weight healthy;
  • Quit smoking. (2)

The list looks long; however, if you make these lifestyle changes, you lower the risk of heart attack, stroke, kidney damage, and other consequences. It looks complex, but it is worth it.


High blood pressure is a disease that needs medical treatment. Hypertension cannot be cured, but the pressure needs to be regulated to prevent stroke or heart attack. Take losartan and other high blood pressure medication as your doctor prescribed, and be aware of your condition.

Read patient information carefully and get familiar with all possible side effects. If you experience any adverse event, talk to your doctor. If you are pregnant or plan to be, talk to your doctor before starting losartan treatment. In case of serious side effects, call your doctor or emergency immediately.

Visit your doctor regularly and follow instructions for medical checks and monitoring of specific parameters even when you feel better. Your doctor and the medication you use can do a lot; you can do even more to get you to feel better.


  1. CDC Centers for Disease Control and Prevention, Facts About Hypertension, 2023 Jan, https://www.cdc.gov/bloodpressure/facts.htm
  2. American Heart Association, The Facts About High Blood Pressure, 2017 Nov, https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure
  3. FDA Food and drug administration, COZAAR® (losartan potassium) tablets, for oral use, 2018 Oct, https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/020386s062lbl.pdf
  4. NIH National Library of Medicine, Losartan, Sana Mulla; Waqas J. Siddiqui., 2022 Jul, https://www.ncbi.nlm.nih.gov/books/NBK526065/
  5. Mayo Clinic, Losartan (Oral Route), 2023 Jan, https://www.mayoclinic.org/drugs-supplements/losartan-oral-route/side-effects/drg-20067341?p=1
  6. Cleveland Clinic, Hyperkalemia (High Potassium), 2020 Oct, https://my.clevelandclinic.org/health/diseases/15184-hyperkalemia-high-blood-potassium
  7. MedlinePlus, Losartan, 2018 Feb, https://medlineplus.gov/druginfo/meds/a695008.html

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About the Author

Biljana Srbinovska
Biljana is a Master of Pharmacy, with a Healthcare Management specialization. Over 20 years of professional engagement to enable access to innovative treatments for patients in need. Biljana is dedicated to upgrading health education evidence-based, promoting a healthy lifestyle, and embedding healthy habits.

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