Losartan is a prescription medication commonly used to treat high blood pressure and protect the kidneys in certain people with diabetes. It belongs to a group of medicines called angiotensin II receptor blockers (ARBs). These medications help relax blood vessels, making it easier for blood to flow and reducing the pressure inside the arteries.
Doctors may also prescribe losartan to reduce the risk of stroke in certain people with high blood pressure and an enlarged heart. It can help slow kidney damage in some patients with type 2 diabetes and high blood pressure. Although losartan is generally well tolerated, it can cause side effects such as dizziness, fatigue, and changes in kidney function or potassium levels.
Understanding what losartan is, why it is prescribed, how it works, and what precautions to follow can help you use this medication safely.
Key Takeaways
- Losartan is an angiotensin II receptor blocker (ARB) used to treat high blood pressure.
- It relaxes blood vessels by blocking the effects of angiotensin II.
- It may help protect kidney function in people with type 2 diabetes and hypertension.
- Common side effects include dizziness, fatigue, and sometimes changes in potassium levels.
- Regular blood pressure checks and blood tests may be needed during treatment.
- Do not stop taking losartan or change your dose without speaking to your healthcare provider.
- Losartan should not be used during pregnancy because it can harm an unborn baby.
What Is Losartan?
Losartan is an antihypertensive medication, meaning it helps lower high blood pressure. Its generic name is losartan potassium, and it is commonly available under the brand name Cozaar, as well as various generic brand names.
It belongs to the angiotensin II receptor blocker (ARB) family. ARBs work by blocking the action of angiotensin II, a natural chemical in the body that causes blood vessels to narrow. When this chemical is blocked, blood vessels can relax and widen, allowing blood to flow more easily.
Losartan is usually taken as an oral tablet. Depending on the condition being treated, a doctor may prescribe it once or twice daily. It can be taken with or without food.
Losartan is not a cure for high blood pressure. Instead, it helps control blood pressure while you continue taking it. Even if you feel healthy, your doctor may recommend continuing treatment to reduce the risk of complications.
What Is Losartan Used For?
Doctors prescribe losartan for several conditions involving blood pressure, the heart, and the kidneys.
1. High Blood Pressure (Hypertension)
The most common use of losartan is treating hypertension. High blood pressure occurs when blood pushes against artery walls with consistently greater force than normal.
Over time, uncontrolled hypertension can damage blood vessels and increase the risk of heart disease, heart attack, stroke, and kidney problems.
Losartan helps lower blood pressure by relaxing blood vessels. It may be prescribed alone or alongside other blood pressure medications when one medicine is not enough to control blood pressure.
2. Kidney Disease in People With Type 2 Diabetes
Losartan may help protect the kidneys in people who have type 2 diabetes, high blood pressure, and diabetic kidney disease.
High blood sugar and high blood pressure can damage the tiny blood vessels inside the kidneys. This damage may allow protein, particularly albumin, to leak into the urine.
By blocking angiotensin II, losartan reduces pressure within the kidney’s filtering system. This can help reduce protein loss in the urine and slow the progression of kidney damage in appropriate patients.
It does not reverse all existing kidney damage, but it may help protect kidney function over time.
3. Reducing Stroke Risk in Certain Patients
Losartan may be prescribed to reduce the risk of stroke in people who have high blood pressure and a condition called left ventricular hypertrophy.
Left ventricular hypertrophy occurs when the muscle wall of the heart’s main pumping chamber becomes thickened. High blood pressure can make the heart work harder, contributing to this change.
By lowering blood pressure, losartan reduces the workload on the heart. In certain patients, this treatment can help lower the risk of stroke.
4. Heart Failure
Losartan may also be prescribed in some cases of heart failure, depending on the patient’s condition and the treatment plan.
Heart failure occurs when the heart cannot pump blood as effectively as the body needs. This can lead to symptoms such as breathlessness, tiredness, and swelling in the legs.
By relaxing blood vessels and reducing the pressure against which the heart pumps, losartan may help reduce the heart’s workload. However, it is not suitable for every person with heart failure, and other medications may be preferred depending on the type of heart failure.
How Does Losartan Work?
To understand how losartan works, it helps to know about a hormone called angiotensin II.
Angiotensin II is part of the body’s renin-angiotensin system, which helps regulate blood pressure and fluid balance. It causes blood vessels to narrow and encourages the body to retain sodium and water. These effects can increase blood pressure.
Losartan blocks angiotensin II from attaching to its receptors, particularly AT1 receptors. As a result, the hormone cannot produce its usual blood-vessel-narrowing effects.
This leads to several changes:
- Blood vessels relax: The arteries become less constricted, allowing blood to flow more easily.
- Blood pressure decreases: Reduced resistance in the blood vessels helps lower pressure.
- The heart works with less resistance: The heart does not have to pump as forcefully against narrowed arteries.
- Kidney pressure may decrease: In certain people with diabetic kidney disease, blocking angiotensin II can reduce pressure inside the kidney’s filtering units and help reduce protein in the urine.
Losartan also reduces the release of aldosterone, a hormone that helps the body retain sodium and water. This contributes to its blood-pressure-lowering effects.
Unlike some other blood pressure medications, losartan generally does not cause the persistent dry cough commonly associated with ACE inhibitors, although individual reactions can vary.
Benefits of Taking Losartan
When prescribed appropriately, losartan can offer several health benefits.
Helps Control Blood Pressure
Losartan helps keep blood pressure within the target range recommended by your healthcare provider. Consistent blood pressure control can reduce the risk of complications affecting the heart, brain, kidneys, and blood vessels.
Supports Kidney Protection
For people with type 2 diabetes and certain forms of kidney disease, losartan can help reduce protein leakage into the urine and slow kidney damage.
May Reduce Stroke Risk
In people with hypertension and left ventricular hypertrophy, losartan may reduce the risk of stroke when used as prescribed.
Reduces Strain on the Heart
By relaxing blood vessels, losartan reduces the resistance the heart must overcome to pump blood. This can be helpful for certain patients with cardiovascular conditions.
Usually Does Not Cause a Persistent Dry Cough
Losartan is an ARB. Compared with ACE inhibitors, ARBs are less likely to cause the persistent dry cough associated with ACE inhibitor treatment. This can make losartan an option for some people who cannot tolerate that side effect.
The benefits depend on the person’s medical condition, dose, and overall treatment plan. Losartan is not intended to replace healthy lifestyle habits or other necessary treatments.
What Is the Usual Dosage of Losartan?
The correct losartan dosage depends on the condition being treated, blood pressure readings, kidney function, age, and response to treatment.
For adults with high blood pressure, a commonly used starting dose is 50 mg once daily. Some patients may be prescribed 25 mg initially, while others may require a higher dose. The dose may be adjusted by the doctor depending on how well blood pressure is controlled.
Losartan tablets are commonly available in strengths of:
- 25 mg
- 50 mg
- 100 mg
These strengths are not instructions for self-treatment. Your doctor will determine the appropriate dose based on your health and treatment needs.
How Should You Take Losartan?
Follow your prescription and take losartan as directed.
- Take it at approximately the same time each day.
- Swallow the tablet with water.
- It can generally be taken with or without food.
- Do not increase or reduce the dose without medical advice.
- Continue taking it even if you feel well, unless your doctor tells you to stop.
Your doctor may recommend regular blood pressure checks and blood tests to monitor kidney function and potassium levels.
What Happens If You Miss a Dose of Losartan?
If you forget to take losartan, follow the instructions provided with your prescription. General guidance is to take the missed dose when you remember, unless it is nearly time for your next scheduled dose.
If it is almost time for the next dose, skip the missed dose and continue with your regular schedule. Do not take two doses together to make up for the missed medication.
Missing an occasional dose may not cause noticeable symptoms, but regularly missing medication can make blood pressure harder to control.
If you have missed several doses or are unsure how to restart your medication, contact your doctor or pharmacist.
Side Effects of Losartan
Like other prescription medications, losartan can cause side effects. Many people tolerate it well, but some may experience mild or more serious reactions.
Common Side Effects
Commonly reported side effects may include:
- Dizziness: Losartan lowers blood pressure, which can sometimes make you feel dizzy, especially when standing up quickly.
- Tiredness: Some people experience fatigue or reduced energy after starting treatment.
- Headache: Headaches may occur, particularly while the body adjusts to changes in blood pressure.
- Nausea: Some people may experience an upset stomach or nausea.
- Muscle cramps: Muscle cramps or weakness may occur in some patients.
- Back pain: Back discomfort has also been reported by people taking losartan.
- Nasal congestion: Some patients may experience a stuffy nose or symptoms resembling an upper respiratory infection.
Not everyone experiences these side effects. If symptoms are persistent, severe, or interfere with daily activities, speak with your healthcare provider.
Serious Side Effects
Although less common, losartan can sometimes cause serious complications.
High potassium levels: Losartan may increase potassium in the blood. This condition is called hyperkalemia. Severe cases can affect the heart’s electrical activity. Muscle weakness, unusual tiredness, or an irregular heartbeat should be assessed promptly.
Kidney function changes: Losartan can affect kidney function, particularly in people who already have kidney problems, are dehydrated, or take certain interacting medications.
Very low blood pressure: Some people may experience a significant drop in blood pressure, leading to severe dizziness, weakness, or fainting.
Allergic reactions: Swelling of the face, lips, tongue, or throat and difficulty breathing may indicate a serious allergic reaction. Seek emergency medical attention if these symptoms occur.
Do not ignore severe symptoms or stop your medication without medical advice, unless you are experiencing a medical emergency requiring immediate care.
Who Should Avoid Losartan or Use It With Caution?
Losartan is not suitable for everyone. Your doctor should know about your medical history before prescribing it.
1. Pregnant Women
Losartan should not be used during pregnancy because it can cause serious harm or death to the developing baby, particularly during the later stages of pregnancy.
If you become pregnant while taking losartan, contact your doctor immediately. Your healthcare provider can help arrange a safer alternative.
2. People With Kidney Problems
People with existing kidney disease may still be prescribed losartan, but they may need closer monitoring.
The medication can cause changes in kidney function, particularly when combined with dehydration or certain other drugs.
3. People With High Potassium Levels
Losartan can increase potassium levels in the blood. People who already have high potassium or conditions that increase the risk of hyperkalemia may require an alternative medication or careful monitoring.
4. People With Liver Problems
The liver helps process losartan. People with impaired liver function may require a lower starting dose or a different treatment plan.
5. People With Low Blood Pressure or Dehydration
If you are dehydrated because of vomiting, diarrhea, excessive sweating, or inadequate fluid intake, losartan may increase the risk of low blood pressure.
Tell your doctor if you are experiencing significant fluid loss or have been advised to restrict fluids.
Losartan Drug Interactions
Losartan can interact with certain medications and supplements. These interactions may increase side effects or affect how well your treatment works.
Some important interactions include:
| Medication or substance | Possible concern |
| Potassium supplements | May increase potassium levels |
| Potassium-based salt substitutes | May increase the risk of high potassium |
| NSAIDs, such as ibuprofen | May affect kidney function and reduce blood pressure control |
| Lithium | May increase lithium levels and toxicity risk |
| Other blood pressure medications | May cause blood pressure to drop too much |
| Other medicines affecting the renin-angiotensin system | May increase the risk of kidney problems, low blood pressure, and high potassium |
Do not start supplements, over-the-counter painkillers, or other blood pressure medications without checking with your doctor or pharmacist.
What Precautions Should You Follow While Taking Losartan?
A few precautions can help you use losartan more safely.
Monitor Your Blood Pressure
Check your blood pressure as recommended by your healthcare provider. Keep a record of your readings so your doctor can evaluate whether the medication is working.
Get Regular Blood Tests
Your doctor may order blood tests to monitor kidney function and potassium levels. These checks are particularly important after starting treatment or changing the dose.
Be Careful When Standing Up
If you feel dizzy, sit or lie down until the sensation passes. Stand up slowly, especially when getting out of bed or a chair.
Avoid Potassium Supplements Without Advice
Do not use potassium supplements or potassium-containing salt substitutes unless your doctor has approved them.
Tell Your Doctor About Illness
Vomiting, diarrhea, fever, and dehydration can affect blood pressure and kidney function while taking losartan. Ask your healthcare provider what to do if you become unwell or cannot keep fluids down.
Do Not Stop Treatment on Your Own
High blood pressure often does not cause noticeable symptoms. Feeling healthy does not necessarily mean your blood pressure is under control. Speak with your doctor before stopping or changing treatment.
Frequently Asked Questions
1. Is losartan a blood thinner?
No. Losartan is not a blood thinner. It is an angiotensin II receptor blocker (ARB) that relaxes blood vessels and lowers blood pressure. It does not work like anticoagulants, which reduce blood clot formation.
2. How long does losartan take to lower blood pressure?
Losartan can begin lowering blood pressure after the first doses, but its full effect may take several weeks. Your doctor may adjust the dose based on your blood pressure readings and response to treatment.
3. Does losartan protect the kidneys?
Losartan can help protect kidney function in certain people with type 2 diabetes, high blood pressure, and diabetic kidney disease. It may reduce protein leakage into the urine and slow the progression of kidney damage.
4. Can losartan cause frequent urination?
Frequent urination is not generally considered one of the main side effects of losartan alone. However, some people take losartan with a diuretic, or water pill, which can increase urination. Speak with your doctor if you notice a persistent change.
5. Can I take losartan at night?
Yes. Losartan can generally be taken in the morning or evening. The important thing is to follow your prescription and take it consistently at the recommended time. Ask your doctor if you are unsure about the best schedule.
6. Does losartan cause weight gain?
Weight gain is not a typical common side effect of losartan. However, unexplained weight gain accompanied by swelling in the legs, ankles, or feet should be discussed with a healthcare provider because it may indicate fluid retention or another medical issue.
7. Can losartan cause a cough?
A persistent dry cough is less common with losartan than with ACE inhibitors such as lisinopril. However, a cough can still occur for other reasons. Discuss a persistent cough with your doctor rather than assuming it is caused by the medication.
8. Can I take losartan with food?
Yes. Losartan can generally be taken with or without food. Taking it at the same time each day can help you maintain a consistent medication routine.
9. What should I do if I accidentally take too much losartan?
Taking more losartan than prescribed may cause low blood pressure, dizziness, or a rapid or slow heartbeat. Seek urgent medical advice if you take an overdose, even if you feel well. Get emergency help if you faint, experience severe weakness, or develop other serious symptoms.
10. Is losartan safe for long-term use?
Losartan is commonly prescribed for long-term blood pressure management. Many people take it for years under medical supervision. Regular blood pressure checks and monitoring of kidney function and potassium help ensure that treatment remains appropriate.
Conclusion
Losartan is an angiotensin II receptor blocker used mainly to treat high blood pressure. It works by blocking the effects of angiotensin II, allowing blood vessels to relax and improving blood flow. In certain patients, it can also help protect kidney function and reduce the risk of stroke.
Although losartan is generally well tolerated, it can cause side effects such as dizziness, fatigue, headache, and changes in potassium levels or kidney function. Taking it as prescribed, attending regular checkups, and following your doctor’s advice can help you get the intended benefits while reducing potential risks.
Medical Disclaimer: This article is for informational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
