Overactive bladder is a condition where the bladder has trouble retaining urine. The most common symptom of overactive bladder is urgency, a sudden need to urinate. However, overactive bladder can also cause frequent urination, night time urination, and leaking urine or a loss of bladder control. Overactive bladder may have many causes and is often the result of nerve problems, diabetes, drinking too much fluid, or taking too much caffeine. Age, previous history of stroke, and alzheimer’s disease may also increase the risk for overactive bladder. Since the cause of overactive bladder varies greatly from person to person, treatment can.