Overactive bladder is a condition where the bladder is unable to hold urine normally. The Urology Care Foundation estimate that at least 33 million people in the United States have overactive bladder. Overactive bladder (OAB) may be caused by an underlying disorder such as Parkinson’s disease, diabetes, multiple sclerosis, or kidney disease. Other times it can be linked to medications, surgery, or childbirth. However, for some people, there appears to be no underlying cause.