Anticholinergic side effects such as dry mouth and constipation are less likely with transdermal oxybutynin than with the oral formulation.3 Application-site reactions occur in at least 10% of patients, and include redness, rash, itching, macule or vesicle formation.1,3,4 Such reactions are usually transient and mild in severity, but were the most common reason for stopping the patches in trials.1,3