OBJECTIVES:  Previous research has described treatment failure as discontinuation of the first anticholinergic or switching in persons with continuous anticholinergic use. Such research does not account for persons who may restart anticholinergic use following a period of discontinuation. The objective of this study was to evaluate the dynamics of treatment failure in patients with OAB following discontinuation of the first anticholinergic. METHODS: Patients in a US commercial database between January 2005 and June 2010 with ≥ 1 filled prescription for an anticholinergic for OAB were included.  Treatment failure was defined as patients who discontinued therapy (treatment gap of ≥45 days) or switched medications.  RESULTS: There were 182,586 patients who met all inclusion criteria. Treatment failure was present in a total of 83.4% patients, with 78.3% of patients discontinuing first anticholinergic therapy and 5.1% of continued users switching.  A total of 30.4% of persons who discontinued treatment rechallenged after the 45 day treatment gap, with 66.7% resuming treatment with their original agent.  Overall, 54.5% of patients discontinued anticholinergic treatment permanently within the one year study period.  A total of 14.1% of patients switched at least once throughout the study, and patients received an average of 1.2 (SD: 0.4) unique anticholinergic agents.  Of those who initially switched to a second anticholinergic, 69.6% of patients failed treatment for a second time either by discontinuing treatment (48.8%) or switching to a third agent (20.8%).  A separate analysis requiring ≥ 2 fills found that 85% of patients who switched also discontinued within the one year study frame. Persons on sustained release anticholinergics were less likely to experience treatment failure than those on immediate release anticholinergics (odds ratio: 0.78 [0.76-0.80], P<0.0001).  CONCLUSIONS: Treatment failure was high in patients taking anticholinergics for OAB even after taking restarts into account. Most patients who switched from their first anticholinergic therapy experienced a second treatment failure.