My 4 year old son weighs 39lbs and was dx with an ear infection. amoxicillin dose is 400mg/5ml 9ml twice daily.... does that dose seem high?

This is appropriate: Appropriate dosing for amoxicillin in treating bacterial ear infections is up to 80 -100 mg per kilogram per day. At 38 pounds I most typically dose 9-10 ml per dose twice daily of the 400 mg/ 5 ml amoxicillin. There is no increase in side effects but it offers improved coverage of resistant bacteria that cause ear infections.

Amoxil (amoxicillin) dose range: The usual dose of Amoxil (amoxicillin) for active bacterial infection in children is generally dosed at 45-90 mg/kg in two divided doses. Your child's dose is just below the highest recommended amount.