How do Botox injections relieve overactive bladder symptoms?

Botulinum A toxin, or Botox, can be used to treat overactive bladder. Botox works by denervating (cutting off the nerve supply to) the bladder muscle and decreasing its contractility. The success rate ranges from 60% to 90%. This can be done in an office with a local anesthetic and lasts five to 12 months and then must be repeated. It is costly, up to $600 to $1,200 per vial, but is now covered by Medicare.

The technique used is to inject into 10 to 30 sites (about 100 to 300 units). The person goes home the same day and usually notices an immediate improvement. One study showed a 50% reduction in weekly incontinence episodes lasting up to nine months.
 

Botox injections are approved by the Food and Drug Administration for relief of overactive bladder symptoms. Clinical trials have shown that people who received injections of 100 units of Botox, delivered through a cystoscope, had to urinate 1.0 to 1.7 fewer times per day, and had 1.6 to 1.9 fewer episodes of incontinence each day. Repeat injections may be needed as your bladder recovers, but should be spaced at least 12 weeks apart.