Clinical trials have shown that Botox has been effective in reducing overactive bladder symptoms. In one trial, patients who were treated with Botox experienced a 50 percent improvement. Another study showed an 88 percent improvement in urgency, frequency and incontinence. Patients also reported an improvement in bladder capacity and in their ability to empty the bladder. The Food and Drug Administration has not yet approved Botox for the treatment of overactive bladder.