13 Losartan Side Effects and How to Manage Them

Close to half of U.S. adults have high blood pressure (hypertension). When left untreated, hypertension raises the risk of heart disease and stroke. In addition to adopting a healthier diet and exercising regularly, taking medications can help lower your blood pressure. Losartan (Cozaar) is an example of a blood pressure medication that many people take.

While safe for most people to take, losartan can cause side effects. Dizziness is common. But digestive side effects, such as nausea, are also possible. So what should you know about losartan side effects? And how can you manage them?

Losartan side effects at a glance

Losartan works well to lower blood pressure, including in people living with kidney disease. Most of its side effects are generally mild and get better with time. But it’s important to watch for more serious issues, especially when first starting the medication.

Common or mild losartan side effects include:

• Dizziness

• Fatigue

• Upper respiratory tract infections

• Cough

• Stuffy nose

• Back pain

• Joint pain

• Nausea

• Vomiting

• Diarrhea

• Headache

• Mildly elevated potassium levels

Rare but serious losartan side effects include:

• Kidney damage

• Severely low blood pressure

• Severely high potassium levels

• Angioedema (swelling of the face, neck, and mouth)

• Allergic reactions

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Losartan also has a boxed warning for birth defects. This is the FDA’s strictest warning for medications. You shouldn’t take losartan if you’re pregnant or trying to become pregnant. There are safer options for managing blood pressure while you’re expecting.

Below, we detail 13 losartan side effects you should know about, plus how to manage them.

1. Dizziness

Losartan lowers blood pressure. But sometimes, it can lower it too much. This can lead to hypotension (low blood pressure). Low blood pressure often makes people feel dizzy.

This side effect is most common when you’re first starting losartan or right after your dose is raised. It’s also more likely to happen if you also take a diuretic (water pill).

Let your healthcare team know if you become dizzy — especially if it worsens or doesn't improve. They may need to lower your losartan dosage.

There are steps you can take to lessen or prevent dizziness. When you wake up in the morning, make sure to get out of bed slowly. This can help prevent orthostatic hypotension, or low blood pressure from quickly changing positions. It’s also a good idea to hold onto something sturdy (like a heavy table or chair) when standing. This can help you remain steady and prevent you from falling.

EXPERT PICKS: WHAT TO READ NEXT

• When to take losartan (Cozaar): Find out what the best time is to take losartan — plus other pharmacist-backed tips for taking it.

• How to take it: Many losartan side effects can be managed with dose changes. Learn about recommended losartan dosages here.

• Things to avoid: Some medications can raise your risk of certain losartan side effects. Read about notable losartan interactions and how to avoid them.

2. Upper respiratory tract infections

About 8% of people taking losartan in clinical trials reported upper respiratory tract infections (URTIs). A slightly smaller number of people taking a placebo (a pill with no medication in it) also reported URTIs. URTIs can include illnesses such as the common cold, the flu, and sinus infections.

It’s unclear why people may be more likely to experience these infections while taking losartan. It could be that people with high blood pressure have a higher risk for respiratory infections than those who don’t.

Staying up to date with vaccinations can help prevent serious complications from some URTIs. This includes getting your annual flu vaccine and making sure your pneumonia vaccine is current. Speak with your healthcare team if you think you’re getting sick more often than usual.

3. Nasal congestion

People taking losartan may also get a stuffy nose (nasal congestion). But it’s fairly uncommon. This side effect may be related to URTIs that people develop while taking losartan.

Nasal congestion should be mild. If you find that it’s severe or persistent, speak with your healthcare team. They may suggest using a neti pot or fluticasone propionate (Flonase). But avoid oral decongestants, such as pseudoephedrine (Sudafed). They can raise your blood pressure.

4. Cough

People who develop a dry cough from angiotensin-converting enzyme (ACE) inhibitors are often switched to a medication like losartan. But losartan can also cause coughs — though much less frequently.

Make sure to tell your healthcare team if you develop a dry, persistent cough, or if your cough continues after switching from an ACE inhibitor. They may recommend switching to a different blood pressure medication.

Keep in mind that other health conditions and medications can also cause persistent coughs. So your healthcare team may want to check for other possible causes.

5. Back pain

People taking losartan may have back pain. It’s unclear why some people have this side effect.

While uncomfortable, pain from losartan should be mild. Let your healthcare team know if the pain is severe or prevents you from moving normally.

People with back pain may get relief from over-the-counter (OTC) creams or patches. Oral OTC pain relievers, such as acetaminophen (Tylenol), can also help. There are also many exercises that you can try at home to relieve back pain.

Discuss the best pain relief option with your healthcare team. Some OTC medications, such as ibuprofen (Advil, Motrin), can raise your blood pressure and should be avoided.

6. Arthralgia (joint pain)

People taking losartan have reported joint pain (also called arthralgia), though this isn’t very common. Similar to back pain, it’s unclear why this happens. But some research suggests that losartan may be less likely to cause joint pain than other blood pressure medications.

If you’re experiencing this losartan side effect, talk to your healthcare team about OTC medications or exercises for joint pain. Generally speaking, relief options that help with back pain also tend to help with joint pain.

7. Fatigue

Tiredness (fatigue) is another possible losartan side effect. It’s one of many blood pressure medications that can make people feel tired. It tends to happen when you first start losartan or after your dose is raised. The effect typically improves over time as your body adjusts to the medication and to a lower blood pressure.

Exercising regularly can help lessen fatigue from losartan. Eating nutrient-dense foods filled with vitamins and minerals may also boost your energy level. If your fatigue is severe or worsens over time, speak with your healthcare team. They may recommend a lower dose of losartan or switching to a different medication.

8. Nausea, vomiting, or diarrhea

It’s also possible to experience digestive side effects while taking losartan. Examples include nausea, vomiting, and diarrhea. Taking losartan with food may help lessen or prevent these issues. And they should improve as your body adjusts to the medication.

Make sure to let your healthcare team know if these symptoms persist or are severe. In very rare cases, people taking losartan developed a complication called sprue-like enteropathy. Symptoms of this condition include severe, chronic diarrhea with significant weight loss. This serious losartan side effect can lead to dehydration and require treatment in a hospital.

9. Headache

Losartan may also cause headaches. This side effect is more common when you first start taking losartan. This can be a sign that the medication is working to lower your blood pressure. Headaches should be mild and get better once your body adjusts to taking losartan.

There are steps you can take at home to help relieve headaches, such as:

• Staying well hydrated

• Getting enough rest at night

• Exercising regularly or adding movement to your routine

• Practicing mindfulness or meditation to help reduce stress

• Limiting caffeine and alcohol

If these don’t help, ask your healthcare team whether you can take OTC pain relievers such as acetaminophen. If your headaches are severe or don’t get better, tell your prescriber. This isn’t typical with losartan, and you should be evaluated.

10. High potassium levels

Losartan can cause high potassium levels (hyperkalemia). In most cases, people only experience mildly high levels. But severely high potassium levels are possible, and they can be harmful if left untreated.

Many people with high potassium levels have no symptoms. That’s why it’s important to get any blood tests your prescriber recommends. These tests help them make sure your potassium isn’t too high. In some cases, they may ask you to temporarily stop losartan until your potassium level returns to normal. But don’t stop taking losartan without your prescriber’s OK.

In rare cases, hyperkalemia can lead to abnormal heart rhythms. These can be life-threatening if left untreated. If you develop a racing heartbeat, chest pain, or shortness of breath, make sure to call 911 or seek immediate medical attention.

11. Birth defects

If you’re pregnant, you shouldn’t take losartan. In fact, the medication includes a boxed warning to avoid it during pregnancy.

This warning is because losartan can cause birth defects. It can interfere with kidney development in fetuses and lower the amount of amniotic fluid (the protective fluid around the fetus). In some cases, these birth defects could be fatal.

There are safer medications to help manage high blood pressure during pregnancy. If you’re considering trying to become pregnant, it’s important to discuss these safer options ahead of time. If you become pregnant while taking losartan, contact your healthcare team right away.

12. Kidney damage

Medications like losartan can help slow the progression of kidney disease. This is especially true for people living with Type 2 diabetes. But in rare cases, losartan can cause acute (sudden) kidney damage.

Medications like losartan can increase the blood level of creatinine (a waste product made by your body). Your kidneys remove creatinine from the body. A high creatinine level can mean that the kidneys aren’t functioning well. In rare cases, high creatinine while taking losartan can be a sign of kidney damage or failure.

Your prescriber may monitor your creatinine levels while taking losartan. It’s important to go for all recommended blood tests. This can help your prescriber catch signs of kidney damage early.

If you notice a sudden decrease in the amount of urine you make or swelling in your legs, contact your healthcare team. These are possible symptoms of kidney failure. It needs to be treated quickly to help prevent serious complications.

13. Chest pain

People taking losartan may sometimes experience chest pain. But chest pain can also be a symptom of other conditions that people taking losartan may have, such as heart disease. Though rare, there are reports of chest pain being directly related to taking losartan.

It’s important to know when to get help for chest pain. Chest pain that gets worse with exertion or happens along with shortness of breath may be a sign of a heart attack. Call 911 immediately if you or a loved one are experiencing this.

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Written by:

Kevin Le, PharmD, BCPS, BCPPS

Kevin Le, PharmD, BCPS, BCPPS is a clinical pharmacy specialist in solid organ transplant at Ann & Robert H. Lurie Children’s Hospital of Chicago. He has been working as a pediatric pharmacist since 2016.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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