Comparative Effectiveness of Available Treatments for Sinus and Ear Infections in Children (Acute Sinusitis)

This study is being conducted at multiple hospitals and clinics to better understand whether antibiotics truly help children feel better when they have a sinus infection (acute sinusitis). Children in the study are randomly assigned (like flipping a coin) to receive either amoxicillin, amoxicillin-clavulanate, or a placebo (a look-alike medicine with no active antibiotic). Neither families nor study staff know which treatment the child is receiving during the study. The main goal is to compare how severe children's symptoms are each day while on these treatments. Parents or caregivers will report symptoms daily using a simple electronic diary. The study will also examine whether factors such as the severity of the child's illness or signs of allergies affect how well antibiotics work. The results will help guide better treatment decisions for children with sinus infections.

Inclusion Criteria: * Age 2 years to \