To investigate the impact of medications on outcomes after tonsillectomy, a retrospective review using the MarketScan database was performed. A total of 306,536 privately insured children and adolescents (1 to 17 years old) who underwent tonsillectomy/adenoidectomy were identified from 2008 to 2012. Pharmaceutical claims identified patients who received outpatient prescriptions for ibuprofen, steroids, or topical anesthetics until discharge and for medications for the treatment of attention deficit hyperactivity disorder (ADHD) or montelukast up to 14 days postoperatively. Logistic regression compared prescription claims to outcomes, including postoperative bleeding, dehydration, emergency department visits, and readmissions. Ibuprofen was the only medication associated with increased odds of postoperative bleeding (odds ratio [OR]: 1.45, 95% confidence interval [CI]: 1.07 to 1.95). Patients receiving steroids had lower odds of dehydration (OR: 0.74, 95% CI: 0.65 to 0.84) and emergency department visits (OR: 0.82, 95% CI: 0.76 to 0.88). Odds of dehydration were highest in patients taking ADHD medications (OR: 1.38, 95% CI: 1.15 to 1.66) and topical anesthetics (OR: 1.32, 95% CI: 1.10 to 1.59). Although causality cannot be assumed in observational studies, steroids and ibuprofen should be used judiciously.