It's not clear whether this is a direct effect of Oxybutinin (which is a recognized side effect) or a drug interaction. 

There are a couple of new drugs recently on the market that have fewer central nervous system (brain) side effects.  These new drugs attach to the brain receptors less and bladder receptors more.  They are Darifenacin (Enablex), Solfenacin (Vesicare) and Trospium Chloride (Sanctura).  Perhaps your doctor can help you with a trial of any of these newer drugs, or a biofeedback program to increase bladder control.

Amy Rosenman, M.D.