ADVERSE REACTIONS The safety and efficacy of oxybutynin chloride was evaluated in a total of 199 patients in three clinical trials. These participants were treated with oxybutynin chloride 5–20 mg/day for up to 6 weeks. Table 3 shows the incidence of adverse events judged by investigators to be at least possibly related to treatment and reported by at least 5% of patients. Table 3 Incidence (%) of Adverse Events Reported by ≥ 5% of Patients Using Oxybutynin Chloride (5–20 mg/day) Body System Adverse Event Oxybutynin Chloride (5–20 mg/day) (n=199) Infections and Infestations Urinary tract infection 6.5% Psychiatric Disorders Insomnia 5.5% Nervousness 6.5% Nervous System Disorders Dizziness 16.6% Somnolence 14.0% Headache 7.5% Eye Disorders Blurred vision 9.6% Gastrointestinal Disorders Dry mouth 71.4% Constipation 15.1% Nausea 11.6% Dyspepsia 6.0% Renal and Urinary Disorders Urinary Hesitation 8.5% Urinary Retention 6.0% The most common adverse events reported by patients receiving oxybutynin chloride 5–20 mg/day were the expected side effects of anticholinergic agents. The incidence of dry mouth was dose-related. In addition, the following adverse events were reported by 1 to < 5% of patients using oxybutynin chloride (5–20 mg/day) in all studies. Infections and Infestations: nasopharyngitis, upper respiratory tract infection, bronchitis, cystitis, fungal infection; Metabolism and Nutrition Disorders: fluid retention; Psychiatric Disorders: confusional state; Nervous System Disorders: dysgeusia, sinus headache; Eye Disorders: keratoconjunctivitis sicca, eye irritation; Cardiac Disorders: palpitations, sinus arrhythmia; Vascular Disorders: flushing; Respiratory, Thoracic and Mediastinal Disorders: nasal dryness, cough, pharyngolaryngeal pain, dry throat, sinus congestion, hoarseness, asthma, nasal congestion; Gastrointestinal Disorders: diarrhea, abdominal pain, loose stools, flatulence, vomiting, abdominal pain upper, dysphagia, aptyalism, eructation, tongue coated; Skin and Subcutaneous Tissue Disorders: dry skin, pruritis; Musculoskeletal and Connective Tissue Disorders: back pain, arthralgia, pain in extremity, flank pain; Renal and Urinary Disorders: dysuria, pollakiuria; General Disorders and Administration Site Conditions: fatigue, edema peripheral, asthenia, pain, thirst, edema; Investigations: blood pressure increased, blood glucose increased, blood pressure decreased; Injury, Poisoning, and Procedural Complications: fall. Postmarketing Surveillance Because postmarketing adverse events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The following additional adverse events have been reported from worldwide postmarketing experience with oxybutynin chloride: Psychiatric Disorders: psychotic disorders, agitation, hallucinations, memory impairment; Nervous System Disorders: convulsions; Eye disorders: cycloplegia, mydriasis; Cardiac Disorders: tachycardia, QT interval prolongation; Gastrointestinal Disorders: decreased gastrointestinal motility; Skin and Subcutaneous Tissue Disorders: rash, decreased sweating; Renal and Urinary Disorders: impotence; Reproductive System and Breast Disorders: Suppression of lactation.