Oxybutynin is used to treat overactive bladder (a condition in which the bladder muscles contract uncontrollably and cause frequent urination, urgent need to urinate, and inability to control urination) in certain adults and children. Oxybutynin is also used as an extended-release tablet to control bladder muscles in adults and children 6 years of age and older with spina bifida (a disability that occurs when the spinal cord does not close properly before birth), or other nervous system conditions that affect the bladder muscles. Oxybutynin is in a class of medications called anticholinergics/antimuscarinics. It works by relaxing the bladder muscles.
Oxybutynin comes as a tablet, a syrup, and an extended-release (long-acting) tablet to take by mouth. The tablets and syrup are usually taken two to four times a day. The extended-release tablet is usually taken once a day with or without food. Take oxybutynin at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take oxybutynin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Summary from MedlinePlus.gov, click for more information.