Volume 10, Number 2Review ArticlesConcomitant Medications and Possible Side Effects of Antimuscarinic AgentsTreatment UpdateScott MacDiarmidAntimuscarinic agents are the treatment of choice for overactive bladder syndrome; clinical experience and the literature support their efficacy, tolerability, and safety. The most common side effects experienced include dry mouth and constipation. Many commonly prescribed drugs have anticholinergic effects that could increase the anticholinergic “load” or “burden” in patients with overactive bladder, potentially increasing the frequency and severity of side effects. In addition, the adverse events associated with antimuscarinics may be more pronounced in the elderly, especially those taking multiple medications. Knowledge regarding the potential side effects associated with antimuscarinics is important so that patients can be advised and effectively treated. [Rev Urol. 2008;10(2):92-98]Overactive bladderOxybutyninAntimuscarinic agentsElderlySide effectsTolterodineSolifenacinDarifenacinTrospium chloride