The primary goal of this study is to determine if the addition of the bladder antispasmotic oxybutynin to standard antimicrobial therapy in the treatment of childhood cystitis will decrease the associated pain and discomfort. A randomized, double blind, placebo-controlled clinical trial design will be used. The second goal of this study will be to describe the nature and duration of symptoms associated with uncomplicated cystitis in the paediatric age group. Finally, adverse side effects associated with short term use of oxybutynin will be monitored.

Roughly half of children age 4 to 16 who are diagnosed with a UTI have cystitis. Adult sufferers of cystitis report terrible scorching with voiding, frequent sensation of the need to void with little results, and aching and pressure in the abdomen and genitals. The management of cystitis in adulthood often includes medication directed at easing pain and discomfort. Little research has been directed at documenting the true incidence of these unpleasant symptoms in paediatric cystitis and virtually no literature exists on the management of the associated pain and discomfort. This study will aim to describe the nature and duration of unpleasant symptoms suffered by children with cystitis and will investigate the efficacy of a possible therapy to ease their suffering.

Hypothesis: The investigators feel that oxybutynin is the most suitable agent for the first trial of bladder antispasmodics in paediatric cystitis. The investigators reasoning is as follows:

1. Previous adult studies have favored an anticholinergic agent (flavoxate) over the topical analgesic phenazopyridine in the symptomatic treatment of cystitis.
2. Newer anticholinergic agents such as oxybutynin and tolterodine have been shown to be superior to older anticholinergic agents (such as flavoxate) in the treatment of many uncomfortable conditions of the bladder.
3. Oxybutynin has been extensively studied in children for several non-infectious conditions of the bladder. The safety profile, expected side effects and dosage range have therefore been established for children.
4. Oxybutynin is marketed in a palatable syrup. A placebo can easily be manufactured that is identical in taste, texture, smell, color, and volume.

The study will be a randomized, double-blind, placebo controlled clinical trial of oxybutynin therapy for symptom control in paediatric cystitis. Toilet trained children aged 4 - 16 years who present to the Alberta Children's Hospital (ACH) emergency room and receive a diagnosis of cystitis are eligible to participate.

Inclusion Criteria:

1. Age 4 - 16 years
2. Suspected diagnosis of cystitis based on a clean catch or catheter urinalysis (must have at least one of the three screening tests positive - leukocyte esterase, nitrites, or leukocytosis or bactiuria on microscopy)
3. Intention to manage patient as an out-patient with oral antibiotics
4. Parent must be available to assist younger children with the measurements for 24 hours and must be willing to receive follow-up calls daily until symptoms resolve
5. Written informed consent (and assent when age-appropriate)

Exclusion Criteria:

1. Clinically suspected pyelonephritis (ED temperature > 38.5, significant flank pain, vomiting > 3 times/24 hours)
2. Patient not toilet trained
3. Patient with significant language delays (preventing use of the facial pain scale)
4. Patient with sensory deficits at the sacral level
5. Inability of the patient and parent to speak and understand English
6. Known contraindication to Oxybutynin (hypersensitivity, glaucoma, bowel obstruction, megacolon, ulcerative colitis, myesthenia gravis, renal or hepatic disease, hyperthyroidism, heart disease, and obstructive uropathy)
7. Patient on any medications during the preceding 8 hours that have analgesic or anticholinergic properties (acetominophen, and inhaled medications will be permitted)
8. Patients who have been previously enrolled in the study
9. Lack of a telephone in the home
10. Known or suspected pregnancy or lactation in the patient
11. Treating physician uses pyridium