Myrbetriq (mirabegron) is a brand-name drug that’s prescribed for overactive bladder in adults and certain children. It’s an extended-release medication. As with other drugs, Myrbetriq can cause side effects, such as headache.

Myrbetriq belongs to a drug class called beta-3 adrenergic agonists. The drug isn’t available in a generic version.

Myrbetriq is available in these oral forms:

  • extended-release tablet
  • extended-release granules that are mixed with water to form a liquid suspension

With extended-release forms, the drug releases slowly into the body over time.

Read on to learn about potential common, mild, and serious side effects of Myrbetriq. For a general overview of the drug, including details about its uses, see this article.

Myrbetriq can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Myrbetriq in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Myrbetriq use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Myrbetriq’s prescribing information.

Mild side effects that have been reported with Myrbetriq include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking Myrbetriq and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Myrbetriq may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Myrbetriq’s prescribing information.

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.

Serious side effects that have been reported include:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Myrbetriq. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below

Myrbetriq is approved to treat neurogenic detrusor overactivity (NDO) in certain children ages 3 years and older.* NDO is a type of overactive bladder (OAB). Side effects of Myrbetriq in children were similar to those in adults.

Side effects in children taking Myrbetriq in clinical trials included:

UTIs were more common in children than adults.

High blood pressure did occur in some children in clinical trials.† Increases in blood pressure were higher in children ages 7 years and younger. It wasn’t reported in children ages 13 years and older.

If you have questions about Myrbetriq’s side effects in children, talk with your child’s doctor. They’ll advise whether the drug is right for your child.

* To learn more about Myrbetriq’s uses, see this article.
† For more information about this side effect, see “Side effect specifics” below.

Myrbetriq may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

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

Myrbetriq’s side effects in older adults (ages 65 years and older) were similar to those seen in younger adults. Clinical trials of Myrbetriq included older adults and adults under 65 years old. There weren’t any overall differences in side effects, safety, or effectiveness between the two age groups.

If you’d like to learn more about Myrbetriq’s side effects in different age groups, talk with your doctor. You can also refer to the drug’s prescribing information.

Can Myrbetriq cause weight gain?

No, taking Myrbetriq shouldn’t cause weight gain as a side effect. It wasn’t reported in clinical trials of the drug. However, urinary tract infections (UTIs) and urinary retention are possible side effects of Myrbetriq.* While these conditions don’t cause weight gain, they can make you feel bloated.

If you’re concerned about weight gain while taking Myrbetriq, talk with your doctor. They’ll help you determine whether Myrbetriq is right for you.

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

Do Myrbetriq’s side effects go away?

Yes, Myrbetriq’s side effects, such as headache, are typically temporary, lasting a few days to weeks. If the side effects don’t go away, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Is hair loss a side effect of Myrbetriq?

No, you’re unlikely to experience hair loss as a side effect of Myrbetriq. It wasn’t reported in the drug’s clinical trials.

If you notice hair loss while taking Myrbetriq, talk with your doctor about possible causes. They may also be able to recommend an appropriate treatment for hair loss.

What are the long-term side effects of Myrbetriq?

Myrbetriq’s side effects are often temporary and go away within a few days or weeks. However, some serious side effects may have long-term effects. For example, urinary retention can lead to bladder or kidney damage.*

Be sure to talk with your doctor if you’re having side effects that aren’t going away or getting better. They can help determine whether you should continue taking Myrbetriq.

* Urinary retention is a serious side effect of Myrbetriq. To learn more, see the “Side effect specifics” section below.

Learn more about some of the side effects that Myrbetriq may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Myrbetriq.

Angioedema

Angioedema was reported in clinical trials of Myrbetriq. Angioedema is sudden swelling of tissues deep in the skin. It often affects the face, lips, tongue, or throat.

Symptoms of angioedema can include:

In some cases, angioedema can occur right after the first dose of Myrbetriq. It has also been reported several hours after the first dose or even after taking many doses of Myrbetriq.

Angioedema can also be a symptom of a severe allergic reaction. When it affects the throat or airways, it can be life threatening.

What you can do

If you have symptoms of angioedema, your doctor will stop treatment with Myrbetriq. They’ll also recommend another treatment that may be a better option for you. To learn more about swelling, see “Allergic reaction” just below.

If your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

High blood pressure

Taking Myrbetriq may cause increases in blood pressure that result in high blood pressure. This was a common side effect in clinical trials of the drug.

High blood pressure typically doesn’t cause symptoms unless it becomes very high (also known as a hypertensive crisis).*

Symptoms of very high blood pressure can include:

  • severe headache
  • nausea or vomiting
  • chest pain
  • changes in vision

High blood pressure occurred in both adults and children taking Myrbetriq.† However, it wasn’t reported in children ages 13 years and older. For details, see the “Side effects in children” section above.

* Hypertensive crisis is a blood pressure of 180/120 millimeters of mercury (mm Hg) or higher.
† Myrbetriq is used to treat overactive bladder (OAB) in adults and certain children ages 3 years and older. To learn more about Myrbetriq’s uses, see this article.

What you can do

Your doctor will monitor your blood pressure during Myrbetriq treatment. They’ll likely recommend that you check your blood pressure regularly. One high reading may not be cause for concern. However, if you have frequent high readings, be sure to tell your doctor. They may recommend a different treatment option for you.

Urinary retention

Urinary retention was reported in clinical trials. With urinary retention, you have trouble emptying your bladder.

Symptoms of urinary retention can include:

  • a feeling of fullness in your bladder
  • lower abdominal discomfort
  • urine leakage
  • needing to urinate more often than is typical
  • trouble starting to urinate
  • a weak urine stream

Some people had to stop taking Myrbetriq in clinical trials due to urinary retention. However, this wasn’t common.

Certain factors can increase the risk of urinary retention as a side effect. This includes taking Myrbetriq in combination with the drug solifenacin (Vesicare).* It also includes having a blockage of urine flow from the bladder. This can occur if you have an enlarged prostate. For details about bladder blockages, see the “Precautions for Myrbetriq” section below.

* Vesicare is a prescription drug used to treat OAB. To learn about other drug interactions with Myrbetriq, see this article.

What you can do

Be sure to talk with your doctor right away if you have symptoms of urinary retention. Your doctor will help determine the cause, such as medications or a blockage. They may change the medications you’re taking or suggest other treatments based on the cause. Without treatment, urinary retention can damage the urinary tract, including the bladder and kidneys.

Urinary tract infection

Urinary tract infection (UTI) was a common side effect in clinical trials of Myrbetriq. A UTI is a bacterial infection of the urinary tract.

UTIs typically affect the lower urinary tract, which includes the bladder and urethra. However, in rare cases, they can become more serious and affect the kidneys.

Symptoms of a UTI can include:

  • burning or pain with urination
  • cloudy or bloody urine
  • fever
  • nausea
  • pain in your sides or the middle of your back
  • frequent or urgent need to urinate

What you can do

If you have symptoms of a UTI, tell your doctor right away. Your doctor will likely have you take a urine test. If the test shows that you have a UTI, they’ll likely prescribe antibiotics. Be sure to take the antibiotics according to your doctor’s instructions.

Allergic reaction

As with most drugs, Myrbetriq can cause an allergic reaction in some people. However, it’s not clear whether this side effect occurred in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Myrbetriq. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Myrbetriq. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Allergic reaction. If you’ve had an allergic reaction to Myrbetriq or any of its ingredients, your doctor will likely not prescribe Myrbetriq. Ask your doctor what other medications may be better options for you.

Antimuscarinic drugs. Taking an antimuscarinic drug (also known as an anticholinergic), such as solifenacin (Vesicare), with Myrbetriq increases the risk of urinary retention. Due to this risk, doctors use caution when prescribing these drugs together. If you take an antimuscarinic drug, tell your doctor before starting Myrbetriq. Ask your doctor about the possibility of drug interactions. For details about Myrbetriq’s interactions, see this article.

Bladder outlet obstruction. People who have a bladder outlet obstruction (BOO) did not show an increased risk of urinary retention with Myrbetriq in clinical trials. (BOO is a blockage between the bladder and urethra that can reduce urine flow out of the body.) Causes of this condition can include an enlarged prostate, scar tissue, or bladder stones.

However, doctors will still use caution when prescribing Myrbetriq to people with an obstruction. If you have a BOO, tell your doctor before starting Myrbetriq. They’ll advise whether it’s the right drug choice for you.

High blood pressure. Myrbetriq can increase blood pressure. So if you have high blood pressure that isn’t managed well with medications, your doctor won’t likely recommend the drug. Before starting Myrbetriq, be sure to tell your doctor that you have high blood pressure. Your doctor may suggest checking your blood pressure more often during Myrbetriq treatment. They can also recommend ways to manage your blood pressure.

Liver or kidney problems. If you have liver or kidney problems, Myrbetriq can build up in your body. This increases the risk of side effects. Due to this risk, your doctor won’t likely recommend Myrbetriq if you have severe liver or kidney disease. If you have liver or kidney problems, tell your doctor before starting Myrbetriq. They may need to adjust the dosage or recommend a different treatment. (For details about Myrbetriq dosages, see this article.)

Alcohol with Myrbetriq

There’s not a known interaction between alcohol and Myrbetriq. However, alcohol can cause some of the same side effects as Myrbetriq, such as dizziness and headache. So consuming alcohol while taking Myrbetriq could make these side effects worse.

Alcohol can also increase the need to urinate and irritate the lining of the bladder. These effects can worsen symptoms of overactive bladder, the condition that Myrbetriq is used to treat.

If you drink alcohol and you’re taking Myrbetriq, talk with your doctor. Ask them what amount, if any, is safe for you to consume during Myrbetriq treatment.

Pregnancy and breastfeeding while taking Myrbetriq

It isn’t known whether it’s safe to take Myrbetriq during pregnancy or while breastfeeding. So be sure to tell your doctor if you’re pregnant or can become pregnant during Myrbetriq treatment. You should also talk with your doctor if you plan to breastfeed.

Together, you can determine whether you should take Myrbetriq. If your doctor advises you not to take the drug, they can recommend other treatments that may be better options for you.

Myrbetriq has some common side effects, some of which are mild. However, serious side effects are possible. If you’d like to learn more about Myrbetriq, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Myrbetriq. For details about other aspects of Myrbetriq, refer to this article.
  • Dosage. For information about the dosage of Myrbetriq, view this article.
  • Cost. To find out about cost and Myrbetriq, refer to this article.
  • A look at your condition. For details about overactive bladder (OAB), see our list of OAB articles.

Disclaimer: Medical News Today 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.