13 Losartan Side Effects and How to Manage Them

Losartan (Cozaar) is a common blood pressure medication. It’s an angiotensin II receptor blocker (ARB) that works well to lower blood pressure, including in people living with kidney disease.

While safe for most people, 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 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. Below is a list of common and rare, but serious losartan side effects to be aware of. Keep in mind that this isn’t a complete list. So be sure to speak with a healthcare professional about any concerning side effects that occur while taking losartan, even if they aren’t listed here.

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 high potassium levels

Rare but serious losartan side effects and reactions include:

• Kidney damage

• Severely low blood pressure

• Severely high potassium levels

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

• Sprue-like enteropathy (intestinal problems)

• Allergic reactions

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), which often makes you feel dizzy.

Dizziness is most common when you’re first starting losartan or right after a dose increase. 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 caused by 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 falls.

2. Upper respiratory tract infections

Upper respiratory tract infections (URTIs) are another possible losartan side effect. URTIs can include illnesses such as the common cold, the flu, and sinus infections.

It’s unclear why you may be more likely to experience these infections while taking losartan. It could be that high blood pressure itself raises the risk of respiratory infections.

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 while taking losartan.

3. Nasal congestion

People taking losartan may also get a stuffy nose (nasal congestion). This side effect may be related to URTIs, but it isn’t common for most people.

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) nasal spray). But avoid oral decongestants, such as pseudoephedrine (Sudafed), unless your prescriber OKs them. 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. It isn’t as common, but losartan can also cause a dry cough in some people. This side effect isn’t harmful, but it can be annoying.

Tell your healthcare team if you develop a dry, persistent cough while taking losartan. They may recommend trying a different blood pressure medication.

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

5. Back pain

People taking losartan may experience back pain. It’s unclear why this side effect happens.

While uncomfortable, back pain from losartan should be mild. You may find relief with over-the-counter (OTC) creams or patches. Oral OTC pain relievers, such as acetaminophen (Tylenol), can also help. There are also exercises you can try at home to help 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. Be sure to let your healthcare team know if back pain is severe or prevents you from moving normally.

6. Arthralgia (joint pain)

People taking losartan have also reported joint pain (arthralgia), though this isn’t very common. Similar to back pain, it’s unclear why this happens. But some research suggests that ARBs such as 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. Fatigue tends to appear when you first start losartan or after a dose increase. But it typically improves over time as your body adjusts to the medication and a lower blood pressure.

Exercising regularly can help lessen fatigue from losartan. Choosing nutrient-dense foods may also help 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 reduce or prevent these issues. And they should improve as your body adjusts to the medication.

Let your healthcare team know if digestive side effects persist or are severe. In very rare cases, people taking losartan may develop 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. Headaches should be mild and get better once your body adjusts to taking it.

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.

10. High potassium levels

Losartan can cause hyperkalemia (high potassium levels). 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 should 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 heart disease and other health conditions. So 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 experience 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:

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.

Reviewed 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.

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