A treatment for an overactive bladder
Mirabegron
A bladder medicine that relaxes the bladder muscle to reduce urgency and frequent urination.
What is Mirabegron?
Mirabegron (Betmiga) treats an overactive bladder. It relaxes the bladder muscle so the bladder can hold more urine, reducing the sudden urge to pass urine, going often, and leaking. Unlike older antimuscarinic bladder medicines it does not cause much dry mouth, but it can raise blood pressure, so this is checked.
Education and reference only. This is a plain-language guide to Mirabegron — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Mirabegron is a medicine for an overactive bladder, where you get a sudden, hard-to-control urge to pass urine, need to go frequently, or leak before reaching the toilet. It works differently from the older antimuscarinic bladder medicines and is often used when those cause too many side effects such as dry mouth. In the UK it is a prescription-only treatment.
How it works
Mirabegron stimulates beta-3 receptors on the bladder muscle, which relaxes the muscle while the bladder is filling. This lets the bladder hold more urine and reduces the sudden urges and frequent trips to the toilet that come with an overactive bladder. Because it works in a different way from antimuscarinics, it causes much less dry mouth and constipation.
Company & origin
Originated / developed by: Astellas (originator).
A bladder medicine of the beta-3 agonist class, used in the UK for overactive bladder.
What it treats
Conditions Mirabegron is used for
Practical use
How to take Mirabegron
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Swallow the tablet whole with water, with or without food; do not crush or chew it.
- Take it at around the same time each day to keep the effect steady.
- Give it a few weeks to work, and keep up bladder-training and lifestyle measures.
- Have your blood pressure checked as advised by your clinician.
- If you miss a dose, take it when you remember unless your next dose is near — do not double up.
Weighing it up
Advantages & disadvantages of Mirabegron
Advantages
- Reduces urgency, frequency and leaking from an overactive bladder.
- Causes much less dry mouth and constipation than older antimuscarinic bladder medicines.
- A useful option when antimuscarinics are not tolerated or not suitable.
Disadvantages
- Can raise blood pressure, so blood pressure must be monitored.
- Not suitable for people with severe uncontrolled high blood pressure.
- May take several weeks to show its full benefit.
Practical use
Good to know
Mirabegron can raise blood pressure, so your blood pressure should be checked before and during treatment, and it is not used if you have severe uncontrolled high blood pressure. It may take a few weeks to see the full benefit, so it is worth giving it time. Bladder training and reducing caffeine often help alongside the medicine. Tell your doctor if you have kidney or liver problems, as the dose may need adjusting.
Who should not take it / use with caution
- People with severe uncontrolled high blood pressure should not take it.
- Used with caution and possibly a lower dose in significant kidney or liver problems.
- Anyone who has reacted to it before; check suitability in pregnancy or breastfeeding with a clinician.
Monitoring
- Blood pressure before starting and during treatment.
- Whether bladder urgency, frequency and leaking improve.
- Kidney and liver function where relevant, as these can affect the dose.
Side effects
- A rise in blood pressure, and sometimes a faster heartbeat.
- Headache, urinary tract infection, or constipation in some people.
- Rarely, a serious allergic reaction or swelling of the face and throat needing urgent care.
Key interactions
- It can raise levels of some other medicines, such as digoxin and certain blood thinners, which may need monitoring.
- Combining it with other medicines that raise blood pressure or heart rate adds to that effect.
- Tell your prescriber about all your medicines, as some doses may need adjusting.
Available as: Prolonged-release tablets taken by mouth.
Answers
Mirabegron: frequently asked questions
How is mirabegron different from antimuscarinic bladder medicines?
Mirabegron relaxes the bladder by stimulating beta-3 receptors, so it causes much less dry mouth and constipation than antimuscarinics like solifenacin. It can, however, raise blood pressure.
Why does my blood pressure need checking?
Mirabegron can increase blood pressure, so it is checked before and during treatment, and it is not used if you have severe uncontrolled high blood pressure.
How long does mirabegron take to work?
It may take a few weeks to see the full benefit on urgency and frequency, so it is worth continuing and giving it time while keeping up bladder-training measures.
Can I take it with an overactive-bladder antimuscarinic?
Sometimes the two are combined under specialist advice, but this should only be done on the recommendation of your clinician, who will monitor you.
Is mirabegron safe in pregnancy?
It is generally avoided in pregnancy and breastfeeding unless a clinician advises otherwise, so discuss your situation with your doctor.
The wider class
About Overactive bladder treatments
Mirabegron belongs to the overactive bladder treatments class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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