Oxybutynin reduces muscle spasms of the bladder and urinary tract. Oxybutynin is used to treat symptomsof overactive bladder, such as frequent or urgent urination, incontinence (urine leakage), and increased night-time urination.
I think that Oxybutynin is used to treat symptoms of muscle spasms of the bladder and urinary tract. The cause of such spasms is another subject and must be investigated by an urologist.