BACKGROUND: Tonsillectomy is associated with postoperative nausea and vomiting 
(PONV) if no prophylaxis is administered. Previous studies have shown that a 
single dose of dexamethasone decreases the incidence of PONV. The most effective 
dose of dexamethasone to affect clinical outcome is yet to be defined.
METHODS: One-hundred-twenty-five children were enrolled in a double-blind, 
prospective, randomized, dose-escalating study of dexamethasone: 0.0625, 0.125, 
0.25, 0.5, or 1 mg/kg, maximum dose 24 mg. Nonparametric ANOVA was used to 
analyze the incidence of vomiting by treatment group for 0 to < or =5 h, >5 to 
24 h. The Cox Proportional Likelihood Ratio Test was used to compare the time of 
first vomit and time to first pain medication across treatment groups.
RESULTS: There was no difference in the incidence of vomiting for the five 
escalating doses of dexamethasone in the time period. There were no differences 
in secondary outcomes (analgesic requirements, time to first liquid, and change 
in voice) across treatment groups.
CONCLUSION: We conclude that the lowest dose of dexamethasone (0.0625 mg/kg) was 
as effective as the highest dose of dexamethasone (1.0 mg/kg) for preventing 
PONV or reducing the incidence of other secondary outcomes following 
tonsillectomy or adenotonsillectomy. There is no justification for the use of 
high-dose dexamethasone for the prevention of PONV in this cohort of children.