5 uncommon side effects of Myrbetriq

In this article:

• Uncommon side effects
• When to discontinue treatment
• The bottom line

In this article

• Uncommon side effects
• When to discontinue treatment
• The bottom line

Myrbetriq (mirabegron) is a brand-name medication used to treat overactive bladder (OAB) in adults. It’s a beta-3 adrenergic agonist that relaxes the bladder muscle and allows the bladder to comfortably hold more urine. This helps you make fewer trips to the bathroom and reduces urinary frequency, urgency, and leakage. 

If you’ve been prescribed Myrbetriq, your healthcare provider may have warned you about the drug’s more common side effects: increased blood pressure, dry mouth, cold-like symptoms, urinary tract infection (UTI), and headache. However, a small number of people taking Myrbetriq have reported a variety of other symptoms, too. Though these aren’t common, they are possible reactions to this medication. Here’s what to know.

What are the uncommon side effects of Myrbetriq?

When prescribing a new medication to one of their patients, healthcare professionals usually explain what a person can expect as far as symptom relief and possible side effects, but they can’t review every possible adverse reaction to a drug. Instead, they usually focus on the most commonly reported side effects or the ones you personally may be at a higher risk of experiencing based on your medical history.

That means you might be prepared for Myrbetriq side effects like a headache or stuffy nose, but not for symptoms like heartburn or palpitations. Though these serious side effects are considered uncommon—they affect 2% or fewer of people taking the drug—they’re still worth knowing about.

Upset stomach

There are a few different gastrointestinal symptoms you might experience on Myrbetriq. In clinical trials, with less than 2% of people taking it reporting constipation, diarrhea, and abdominal pain. The prescribing information for Myrbetriq also indicates that fewer than 1% of people have reported heartburn, bloating, and stomach inflammation. 

It’s not clear from existing studies how soon after starting Myrbetriq these GI symptoms begin or if they usually go away over time, says Christopher Kannady, MD, urologist at CLS Health in Texas. In general, Myrbetriq side effects resolve on their own as your body adjusts to the medication, but some last as long as you’re taking the drug.

Myrbetriq can be taken with or without food, but taking it with food could help ease some of your GI symptoms. You can also manage temporary GI side effects with over-the-counter (OTC) medications, says Dr. Kannaday. Think: antacids for heartburn, Imodium (loperamide) for diarrhea, and stool softeners for constipation.

Glaucoma 

It’s technically true that Myrbetriq has been associated with rare cases of angle-closure glaucoma, but according to Jason B. Carter, MD, urologist and medical advisor at Aeroflow Urology, most people don’t need to worry. Unless you have a history of narrow-angle glaucoma, the risk is negligible. It was reported in fewer than 1% of people, and primarily in what’s called post-marketing surveillance, says Dr. Carter. (This means during the manufacturer’s continued monitoring of patients after the drug is approved and being used by patients.)

Even in people with other types of glaucoma, Myrbetriq hasn’t been found to cause or worsen symptoms. However, Dr. Carter says if you experience any eye pain, blurred vision, or halos around lights while taking this drug, especially at the start of treatment, you should contact your provider right away or get immediate medical care to prevent complications.

Sinus infections 

Nasopharyngitis, or inflammation of the nose and throat, occurs in 3%-4% of people taking Myrbetriq. The drug can make you feel as if you have a cold, causing a stuffy or runny nose, cough, or sore throat.  

Although sinus infections aren’t considered a common side effect of Myrbetriq (they’ve been reported in fewer than 1% of people), Dr. Carter says he’s had some of his own patients report ongoing nasal congestion and sinus infections after starting the drug: “[Myrbetriq has a] mild drying effect on mucosal surfaces, which could interfere with normal sinus drainage, especially in those with allergies or a prior history of chronic sinusitis.”

Sinus symptoms are usually an early side effect of treatment, Dr. Carter says, appearing in the first few months. If your symptoms are mild, he recommends treating them by drinking plenty of water, using saline rinses, and running a humidifier in your bedroom at night.  

Cardiovascular changes 

About 7%-11% of people taking Myrbetriq will experience high blood pressure or hypertension because of how the drug works. Although it targets beta-3 receptors in the bladder, beta-3 receptors are also found in your circulatory system. Sometimes Myrbetriq affects these receptors, causing cardiovascular side effects, says Dr. Kannady. In addition to hypertension, it may also cause tachycardia (high heart rate) and heart palpitations, though these symptoms have been reported in fewer than 2% and 1% of people, respectively 

Heart rate symptoms like tachycardia and palpitations may go away after being on Myrbetriq for a few weeks, says Dr. Carter, or they can persist as long as you’re taking the drug. If your symptoms are mild, follow your provider’s advice about when to get in touch; they may tell you to monitor your symptoms and contact them if they don’t get better in a few weeks, or they may want to hear from you right away. 

You should get immediate medical care for any of the following symptoms:

• Chest pain
• Shortness of breath
• Weakness
• Dizziness, lightheadedness, or fainting

Kidney stones 

Kidney stones aren’t a commonly reported side effect of Myrbetriq. But Myrbetriq works by helping you use the bathroom less frequently, which can lead to more concentrated urine or urine that remains in your bladder for longer periods of time, potentially causing an environment that’s more favorable to kidney stone production after several months on the medication, says Dr. Carter. 

This risk is higher for some people compared to others: “In my experience, [this side effect] tends to occur in patients who already have a predisposing factor, such as a personal history of stones, low fluid intake, or incomplete bladder emptying,” Dr. Carter explains.

If you have a history of kidney stones, Dr. Carter says staying well hydrated and regularly using the bathroom throughout the day can help prevent them. If you develop a stone while taking Myrbetriq, he says your healthcare provider should work with you to determine if it was the medication or not before choosing whether to continue it. 

When to discontinue Myrbetriq

Many of the common and uncommon side effects of Myrbetriq appear when you first start taking the medication and go away on their own after a few weeks as your body adjusts, says Dr. Carter, especially side effects like headache, GI upset, and a slight increase in heart rate. Other side effects—like hypertension and urinary retention—tend to last for as long as you’re taking it. 

It’s important to have your heart rate and blood pressure regularly monitored while you’re on Myrbetriq to make sure it’s safe for you to continue taking it. “There are a few situations where I would advise stopping Myrbetriq [and] the most common is a sustained increase in blood pressure,” says Dr. Carter. “Even a modest rise in systolic pressure can become problematic in a patient who’s already at cardiovascular risk.”

Another reason you may need to stop taking Myrbetriq? Urinary retention, which Dr. Carter says can increase the risk of UTIs or even cause kidney damage. 

Finally, some medications may interact with Myrbetriq, increasing your risk for side effects. For example, side effects like urinary retention, dry mouth, and constipation are more common when Myrbetriq is taken with other OAB drugs like Vesicare (solifenacin succinate).

Keep in mind that everyone taking Myrbetriq will respond differently to the medication and have a unique experience when it comes to side effects and their duration. Plus, what’s tolerable for you might not be tolerable for someone else. If your side effects are persistent, getting worse, or interfering with your quality of life, seek medical advice from your healthcare provider. You may be able to lower your dose or make a lifestyle change that improves your side effects. Your provider may also want to discuss how well Myrbetriq is actually working for you to determine if the benefits are worth the side effects, says Dr. Carter.

This medication can very rarely cause a serious allergic reaction, called angioedema, that causes swelling of the face and mouth. It can be life-threatening and requires immediate medical attention.

The bottom line

Myrbetriq can help relieve symptoms of overactive bladder, helping you use the bathroom less urgently and frequently. But like all prescription drugs, it has the potential to cause side effects. Your provider might warn you about symptoms like hypertension and UTIs, but a small number of people (fewer than 2%) have also reported side effects like upset stomach, heart palpitations, kidney stones, glaucoma, and sinus infections in both clinical trials and post-marketing surveillance. Some of these side effects are temporary after starting the medication, but others can persist.

You shouldn’t expect to have uncommon side effects when taking Myrbetriq, but it’s helpful to know they’re a possibility so you can talk to your healthcare provider if you think the medication is causing them. Your provider may lower your dose, offer suggestions for managing any temporary side effects, or help you weigh the pros and cons of staying on the medication.