What is the primary side effect of urinary antispasmodics like oxybutynin?

Oxybutynin, a urinary antispasmodic, primarily acts by relaxing the bladder muscles to reduce involuntary contractions, making it effective for treating overactive bladder symptoms, such as urinary urgency and frequency. The primary side effects associated with the class of medications, including oxybutynin, are often due to their anticholinergic properties. These properties can lead to reduced secretions in the body, which is why patients commonly experience dry mouth and constipation.

Dry mouth occurs as the medication inhibits salivary gland function, while constipation arises from decreased gastrointestinal motility. These side effects are significant and often more pronounced than other potential side effects, making them a primary concern when prescribing this medication. Overall, understanding the physiological mechanism behind oxybutynin's action helps clarify why dry mouth and constipation are the most prevalent side effects encountered in patients.