Usual adult dose by mouth is 500 mg to 1000 mg every 4 to 6 hours up to maximum of 4000 mg daily.
Children <3 months: 10 mg per kg body weight; 3 months to 1 year: 60 to 120 mg; 1 to 5 years: 120 to 250 mg; 6 to 12 years: 250 to 500 mg.
Or as prescribed by the physician.