Following a description of the historic evolution of botulinum toxin A detrusor injections for neurogenic and nonneurogenic bladder overactivity, which was mainly driven by German-speaking countries, the terminological revolution of 2002 and the influence on design and outcomes of upcoming approval studies for the indication overactive bladder (OAB) are examined. OnabotulinumtoxinA (100 IU) for second-line treatment of OAB received European approval in 2013. Phase IV observational studies concerning therapeutic persistence and adherence with onabotulinumtoxinA are analyzed and compared with therapeutic alternatives. Predictors of treatment success and complications are identified and compared to the required preinterventional diagnostic effort. Since onabotulinumtoxinA and sacral neuromodulation (SNM) are competing for second-line OAB treatment, both options are compared with regard to differential indications, effectivity, durability and patient adherence. Gender-specific causes of urgency and urge incontinence in women are differentiated from the diagnosis of OAB and require priority treatment. On the basis of diagnostic examination results, an algorithm for invasive second-line treatment of OAB is presented, since overly liberal utilization of onabotulinumtoxinA in therapy-naive OAB patients has not proven superiority over oral antimuscarinergic standard therapy, which can only be explained by improper patient selection.