If you have certain medical conditions that cause overactive bladder (OAB), your doctor might suggest Myrbetriq as a treatment option.

Specifically, Myrbetriq is a prescription drug used to treat:

  • OAB in adults with urinary incontinence symptoms such as urinary urgency and frequency. For this use, Myrbetriq is prescribed alone or together with Vesicare (solifenacin).
  • Neurogenic detrusor overactivity (NDO) in some children. NDO is a condition that causes uncontrolled contractions in the detrusor muscle of the bladder.

The active ingredient in Myrbetriq is mirabegron. (An active ingredient is what makes a drug work.)

Myrbetriq comes as an extended-release tablet that you swallow. For children, Myrbetriq also comes as granules that are added to water to make an extended-release liquid suspension they swallow.

Some people may need to take Myrbetriq long term.

For more information about Myrbetriq, including details about its uses, see this in-depth article.

Like other drugs, Myrbetriq can cause mild to serious side effects. Keep reading to learn more.

Below are just a few of the more common side effects reported by people who took Myrbetriq in studies. These side effects can vary depending on the condition the drug is being used to treat.

More common side effects in people taking Myrbetriq for overactive bladder include:

More common side effects in people taking Myrbetriq for neurogenic detrusor overactivity (NDO) include:

  • the common cold
  • constipation
  • headache
  • UTI*

* To learn more about this side effect, see the “Side effects explained” section below.

These are just a few of the commonly reported side effects this drug can cause. The following sections include more. But note that side effects won’t happen to everyone.

Myrbetriq may cause mild side effects. Examples that have been reported with this drug include:

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Myrbetriq unless your doctor recommends it.

Myrbetriq may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

Serious side effects from Myrbetriq are rare but possible. Serious side effects that have been reported with this drug include:

If you develop serious side effects while taking Myrbetriq, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.
† To learn more about this side effect, see “Allergic reaction” in the “Side effect explained” section below.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Myrbetriq, visit MedWatch.

Myrbetriq is used to treat neurogenic detrusor overactivity (NDO) in children ages 3 years and older who weigh at least 35 kilograms (kg).*

Children taking Myrbetriq for NDO may experience different side effects than adults. Constipation is a common side effect of this drug in children. The rates that other side effects occur may differ between adults and children.

Some other common side effects of Myrbetriq in children include:

* One kg equals about 2.2 pounds (lb).
† To learn more about this side effect, see the “Side effects explained” section below.

Below are answers to some frequently asked questions about Myrbetriq’s side effects.

How do the side effects of Myrbetriq in older adults compare with those seen in younger adults?

There was no difference in side effects in older adults (ages 65 years and above) compared with younger adults in Myrbetriq’s studies.

But some older adults may use a combination of Myrbetriq and Vesicare (solifenacin).

Vesicare belongs to a group of drugs called muscarinic receptor blockers. These drugs affect muscle contractions in the bladder. By doing so, they help control urinary incontinence in a different way than Myrbetriq does. Older adults are more sensitive to the side effects of muscarinic receptor blockers, such as Vesicare, than younger adults.

Side effects such as dry mouth, constipation, and urinary retention may be more likely in older adults taking Vesicare. Muscarinic receptor blockers can also cause cognitive problems, including worsening dementia and delirium. These cognitive issues can lead to behavioral problems and loss of ability to perform daily tasks.

The risk of side effects from Myrbetriq may also be more likely in people taking many different drugs.

If you’re concerned about the risk of side effects from Myrbetriq, talk with a doctor or pharmacist.

Do the different strengths of Myrbetriq, including 25 mg and 50 mg, cause different side effects?

The different strengths of Myrbetriq, including the 25-milligram (mg) and 50-mg doses, are unlikely to cause different side effects. But certain side effects may be worse at higher doses of the drug. For example, in studies, people taking the higher dose of Myrbetriq had a greater increase in blood pressure.

Is weight gain a side effect of Myrbetriq?

No. Weight gain wasn’t a reported side effect in studies of Myrbetriq. But if you have difficulty emptying your bladder (urinary retention), your weight may appear higher since your body is retaining fluid. Along with weight gain, you may have other symptoms of urinary retention, such as:

If you think you have urinary retention, talk with your doctor. They may have you stop taking Myrbetriq or switch you to a different treatment.

If you’re concerned about weight gain with Myrbetriq, talk with your doctor. They can help find the cause and if necessary, help you develop a nutrition and exercise plan to manage your weight.

Does Myrbetriq cause hair loss or memory loss?

No. In studies, Myrbetriq didn’t cause hair loss. If you’re concerned about hair loss, talk with your doctor. They can provide more information, including helping you find the cause if necessary.

Some people may have problems with behavior and other psychological side effects from some drugs used for urinary incontinence. But Myrbetriq is unlikely to cause memory loss.

Vesicare (solifenacin) is a type of urinary incontinence drug that people may take together with Myrbetriq. This drug combination is safe. But some people, such as adults ages 65 years and older, may be more at risk of side effects from Vesicare.*

This includes mental health and behavioral problems, such as:

If you’re concerned about memory loss with Myrbetriq and Vesicare, talk with your doctor.

*See the “How do the side effects of Myrbetriq in older adults compare with those seen in younger adults?” question and answer above.

Learn more about some of the side effects Myrbetriq may cause.

Urinary retention

Urinary retention is when you’re unable to empty your bladder. People with a condition called bladder outlet obstruction (BOO) who are taking Myrbetriq may develop urinary retention. But this is a rare side effect.

Combining Myrbetriq with another group of drugs called muscarinic receptor blockers, which are used for urinary incontinence, may also increase your risk of urinary retention.

Signs and symptoms of urinary retention include:

What might help

While Myrbetriq may cause urinary retention in some situations, it’s a rare side effect. If you’re taking Myrbetriq for BOO, your doctor will monitor you closely for any signs of urinary retention.

If you’re taking Vesicare (solifenacin), a muscarinic receptor blocker, your doctor will follow up with you frequently to check for urinary retention. Report any symptoms of urinary retention to your doctor immediately.

High blood pressure

Some people may have increases in blood pressure while taking Myrbetriq. People with high blood pressure can still take this drug, but their doctor will monitor their blood pressure more closely. Blood pressure increases are likely with higher doses of Myrbetriq.

Increases in blood pressure can occur in children as well. Younger children (ages 3 years through 11 years) may have larger increases in blood pressure while taking Myrbetriq.

What might help

Doctors usually don’t prescribe this drug for people with severe high blood pressure or when blood pressure is not well managed. If you have high blood pressure and your doctor prescribes Myrbetriq for you, they’ll likely have you monitor your blood pressure at home. You can then report any increases at your follow-up appointments.

Urinary tract infection (UTI)

UTI is a common side effect of Myrbetriq. This is also known as a bladder infection. Bacteria in the bladder or other structures of the urinary tract cause infections. Symptoms of a urinary tract infection include:

These symptoms are similar to urinary incontinence symptoms, but without antibiotic treatment, they may worsen.

What might help

If you think you have a UTI, talk with your doctor. They’ll order a test to check your urine for bacteria. Sometimes UTIs resolve on their own without treatment, but your doctor may prescribe an antibiotic to treat it. If you have frequent urinary tract infections with Myrbetriq, talk with your doctor.

If you have fever, chills, nausea, or back pain, call your doctor immediately. This can be a sign of a more serious infection.

Dry mouth

Dry mouth is a side effect that some people have with Myrbetriq. Older adults may be more at risk of dry mouth. But rates of side effects in general between younger and older adults were similar in studies.

Dry mouth symptoms include:

  • a burning sensation in your mouth
  • trouble swallowing
  • changes in taste

What might help

Some strategies that may help to relieve dry mouth include:

  • avoiding caffeine, tobacco, and alcohol
  • avoiding dry and hard foods
  • maintaining regular oral hygiene and dental care
  • avoiding or treating dehydration
  • chewing sugar-free gum or sucking on sugar-free candy
  • frequently sipping water

Your dentist may also help you choose toothpastes, mouthwashes, and other products that address dry mouth. If this side effect is bothersome, talk with your doctor. They can recommend a different treatment for your condition that causes less dry mouth.

Allergic reaction

Like most drugs, Myrbetriq can cause an allergic reaction in some people. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, usually in your eyelids, lips, hands, or feet

Some people may develop angioedema. This is swelling of the face, lips, tongue, or throat, which can make breathing difficult. This can occur after the first dose or after multiple doses.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an antihistamine you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Myrbetriq, they’ll decide if you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, stop taking Myrbetriq. Call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Myrbetriq, they may have you switch to a different treatment.

Keeping track of side effects

During your Myrbetriq treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Myrbetriq affects you. They can then use this information to adjust your treatment plan if needed.

Myrbetriq may not be right for you if you have certain medical conditions. (This is known as a drug-condition interaction.) Other factors may also affect whether this drug is a good treatment option for you. Talk with your doctor about your health history before starting Myrbetriq. Factors to consider include those described below.

Kidney or liver problems. Having kidney or liver problems may cause the levels of Myrbetriq to build up in your body. This increases your risk of side effects. Talk with your doctor if you have kidney or liver problems before starting Myrbetriq. They’ll decide whether the drug is safe for you.

High blood pressure. Myrbetriq can increase your blood pressure. Due to this risk, doctors usually won’t prescribe Myrbetriq to people with untreated high blood pressure. If your blood pressure is well managed, this drug may be safe for you. Your doctor may instruct you to check your blood pressure at home. And they’ll have a healthcare professional check it during your Myrbetriq follow-up visits to be sure it’s in a safe range. For more information, see the “Side effects explained” section above.

Urinary retention. People with a condition called bladder outlet obstruction (BOO) have a risk of urinary retention as a side effect of Myrbetriq. For more information, see the “Side effects explained” section above.

Allergic reaction. If you’ve had an allergic reaction to Myrbetriq or any of its ingredients, your doctor will likely not prescribe it for you. Angioedema (swelling of the face, lips, tongue, and throat) can occur while taking Myrbetriq. Some people have experienced this after their first dose, some after multiple doses. If your doctor suggests you stop taking Myrbetriq because of an allergic reaction, they’ll suggest other treatment options for your condition.

Alcohol and Myrbetriq

Some drugs interact with alcohol, but Myrbetriq isn’t one of them. But drinking alcohol may have negative effects on urinary problems such as incontinence.

If you drink alcohol, ask your doctor about how much, if any, could worsen your condition.

Pregnancy and breastfeeding while taking Myrbetriq

There is not enough information from studies about the safety of Myrbetriq use during pregnancy or breastfeeding.

If you’re pregnant or planning to become pregnant while taking this drug, talk with your doctor.

If you’re considering breastfeeding, your doctor can help you weigh the benefits of breastfeeding with the possible risks Myrbetriq may pose to your child.

Side effects with Myrbetriq are usually mild and temporary. Severe side effects are rare. Tell your doctor about any bothersome or long-lasting side effects you may have with this drug.

Questions to ask your doctors may include:

  • Is my risk of side effects greater if I take Myrbetriq without food?
  • Will taking Myrbetriq at nighttime reduce my risk of side effects?
  • Does Myrbetriq have fewer side effects than other urinary incontinence drugs, such as Vesicare (solifenacin)?
  • When do mild side effects of Myrbetriq usually go away?
  • Are any side effects of Myrbetriq different for males than for females*?

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

To learn more about Myrbetriq, see these articles:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.