Dosage in children: 5 mg/kg body weight up to 8.8mg/kg/. Dosage in adults: 200 to 300 mg/day. The daily dosage should be divided into 2 to 3 daily portions. Amantadine is a safe drug with mild side effects: headache, decreased appetite, sedation, fatigue, abdominal pain, vomiting, insomnia, pedal edema and rash (4-10).