The investigators' study will involve the administration of either placebo or celecoxib to children aged 2 to 18 years of age undergoing tonsillectomy and assessing pain relief, impact on quality of life and side effect profile.

The study will consist of two arms, one placebo and the other celecoxib. To establish baseline data on the day of surgery the parents will be required to complete a validated parent report quality of life inventory, multi-dimension fatigue scale and pediatric pain questionnaire for the preceding week. Children/adolescents aged 8 to 18 years of age will be required to complete a child self-report of the same modules. Children undergoing adenotonsillectomy will receive either placebo or celecoxib by mouth one hour prior to their surgery. They will all receive preoperative acetaminophen. Premedication with midazolam will be at the discretion of the attending anesthesiologist. The patients will undergo a standardized anesthetic protocol including postoperative management of pain and nausea and vomiting. The patients, while under anesthesia, will have blood drawn to screen for occult liver and kidney disease, determine their CYP2C9 genotype and reserve for future gene chip micro array analysis.

Patients in both study arms will receive a second dose of celecoxib or placebo by mouth in the evening after surgery and then consecutively in the morning and evening for 72 hours. For seven days after the surgery the families will record once a day pain scores, document analgesic use and any side effects or adverse events. The families will be contacted by phone in the evening of the first three postoperative days to ensure that they understand and are completing the required documentation. On the seventh postoperative day the parents and children aged 8 to 18 years of age will be contacted by phone and instructed to complete the same two validated questionnaires concerning quality of life and level of fatigue completed on the day of surgery. Parents of children less than eight years of age will be responsible for completing these questionnaires based on observations of their children. On the 11th postoperative day the families will be contacted by e-mail or regular mail to complete a questionnaire asking about the extent of contact with the healthcare system, bleeding complications, recovery and overall satisfaction with their care.

Inclusion Criteria:

• Children aged 2-18 years
• Tonsillectomy, or adenotonsillectomy
• No exclusion criteria

Exclusion Criteria:

• Age < 2yrs and >18yrs old
• BMI < 10th or > 95th percentile
• Serum creatinine (Cr) > 2 X UNL (upper normal limit)
• Abnormal liver function; namely alanine aminotransferase (ALT) > 1.5 X UNL, alkaline phosphatase (ALP) > 5X UNL, total bilirubin > 2 X UNL
• History of peptic ulcer disease.
• History of bleeding disorders
• History of severe asthma (requiring recent hospital admission or oral corticosteroid therapy)
• Allergy to celecoxib, sulfonamide compounds or NSAIDs
• Patients receiving CYP2C9 inhibitors fluconazole, amiodarone and oxandrolone
• Patients receiving CYP2C9 inducers rifampin and phenobarbital
• Extremes of body mass index (BMI) (age related below10th or above 90th percentile)
• Parents of any participants, irrespective of age, who are unable to read and understand instructions relayed in English or French
• Participant and/or parents of any participants, irrespective of age, who suffer from dementia, psychosis, significant developmental delay or other impairment that would prohibit the understanding and giving of informed consent or assent or the participation in self-care or toxicity reporting