Botulinum toxin injections into the bladder

This card explains botulinum toxin injections into the bladder, a treatment for overactive bladder that has not responded to simpler measures. It covers the purpose, the outline of the procedure, the recovery and the risks that guidelines and hospital leaflets list. It is general information for patients and students, and a person's own clinician decides what fits their situation.

What it is

Botulinum toxin type A (often called Botox) is a medicine used for several muscle disorders, including overactive bladder. An NHS hospital leaflet from University Hospital Southampton explains that overactive bladder is caused by overactivity of the bladder wall muscle, which produces urinary frequency, urgency and often leakage. The toxin works by stopping that muscle from contracting too much. See the glossary for terms.

The treatment is not permanent. The same leaflet says benefits are expected to last six to nine months, with variation between individuals, and that most women will need further treatments.

Why it is done

Botulinum toxin is generally considered after other approaches have been tried. The 2024 American Urological Association guideline on idiopathic overactive bladder says that for people who have an inadequate response to, or intolerable side effects from, medication or behavioral therapy, clinicians should offer sacral neuromodulation, percutaneous tibial nerve stimulation, and/or intradetrusor botulinum toxin injection. The card on sacral neuromodulation describes one of the alternatives.

The NICE guideline on urinary incontinence in women recommends that, after review by a local multidisciplinary team, women with overactive bladder caused by detrusor overactivity that has not responded to non-surgical management, including medicines, be offered bladder wall injection with botulinum toxin type A. The Southampton leaflet states that the treatment works for 75 percent of women who have it.

How it is done, in outline

The injections are given through a cystoscope, a thin tube with a camera that is passed through the urethra into the bladder (see the card on cystoscopy). In most cases a local anesthetic gel numbs the urethra, though some people have sedation or general anesthesia. The Southampton leaflet says the surgeon makes ten to twenty small injections into specific sites in the bladder wall muscle, usually with the tube in place for less than five minutes.

Before treatment, the AUA guideline says clinicians should measure post-void residual, meaning the urine left in the bladder after passing water.

Recovery

The Southampton leaflet says people may be asked to stay for a couple of hours until they have passed urine and feel well, with a bladder scan to check that the bladder empties. An antibiotic is usually given, by injection or tablet. The leaflet says people can return to work the day after, and that most notice improvement within three to four days, although for some it takes up to three weeks.

A follow-up conversation with a specialist nurse is typical, and before it the team may ask the person to try a self-catheter to see whether urine is left behind. The AUA guideline advises obtaining a post-void residual if symptoms have not improved enough, or have worsened, after injection. For general advice on catheters, see urinary catheters after surgery and the recovery and rehabilitation hub.

Risks

Difficulty emptying the bladder (urinary retention) is the best-known risk. The Southampton leaflet says up to one in 20 women may have difficulty emptying fully, which is usually temporary, lasting days or weeks, but can sometimes last until the effect of the toxin has worn off. A small number with severe problems may need a catheter up to five times a day. The Cleveland Clinic gives a range of about 5 to 8 percent for retention, and says affected people may need temporary catheterization. The sources use different figures.

NICE says treatment should begin only if the woman is willing to perform clean intermittent catheterization regularly for as long as needed if significant voiding problems develop, or to accept a temporary indwelling catheter if she cannot do so. NICE also lists an increased risk of urinary tract infection (UTI) among the adverse effects to discuss, and states that there is not much evidence on how long injections work, how well they work in the long term, and their long-term risks. The Cleveland Clinic reports that the makers of the drug cite a UTI rate of 18 percent. The Southampton leaflet says between one in 10 and one in 50 people may have repeated UTIs.

The Southampton leaflet says blood in the urine is usually minor, and that in extremely rare cases (fewer than one in 10,000) the toxin can spread to other parts of the body, with muscle weakness that may affect swallowing, speech or breathing. It advises contacting a GP or NHS 111 if these occur, and calling 999 or going to an emergency department in an emergency.

Questions to ask your clinician

• Which treatments have I already tried, and which others remain available for my symptoms?
• How likely is it that I will have trouble emptying my bladder, and how will that be checked?
• Will I be taught clean intermittent catheterization before the injections, and can I get supplies?
• How long do the effects usually last, and how often might injections be repeated?
• Which symptoms should lead me to call the clinic, my GP or an emergency service?