What is the appropriate dosage of amoxicillin (amoxicillin) for a 9-month-old child?

Amoxicillin Dosing for a 9-Month-Old Child

For a 9-month-old infant, amoxicillin dosing depends on the indication: for mild to moderate respiratory infections use 45 mg/kg/day divided into 2 doses (approximately 22.5 mg/kg per dose twice daily), while severe infections or areas with high pneumococcal resistance require 90 mg/kg/day divided into 2 doses (approximately 45 mg/kg per dose twice daily). 1

Dosing by Clinical Indication

Respiratory Tract Infections (Most Common)

• Mild to moderate pneumonia or respiratory infections: 45 mg/kg/day divided every 12 hours (or 40 mg/kg/day divided every 8 hours) 2, 1

• Severe pneumonia or high-resistance areas: 90 mg/kg/day divided every 12 hours is the preferred regimen 2, 1

• For a typical 9-month-old weighing approximately 9 kg, this translates to roughly 200 mg twice daily for mild infections or 400 mg twice daily for severe infections 3

Group A Streptococcal Infections

• Recommended dose: 50-75 mg/kg/day divided into 2 doses 2, 1

• Treatment must continue for at least 10 days to prevent acute rheumatic fever 3

Ear/Nose/Throat and Skin Infections

• Mild to moderate: 25 mg/kg/day divided every 12 hours (or 20 mg/kg/day divided every 8 hours) 3

• Severe infections: 45 mg/kg/day divided every 12 hours (or 40 mg/kg/day divided every 8 hours) 3

Critical Dosing Considerations for Infants

• For infants under 12 weeks (3 months), the maximum recommended dose is 30 mg/kg/day divided every 12 hours due to immature renal function 3

• For infants 3 months and older, standard pediatric dosing applies based on weight and severity of infection 3

• The 250 mg dose mentioned in your question would be appropriate for a 9-month-old only if treating a mild infection in a child weighing approximately 10 kg, given twice daily (total 500 mg/day = 50 mg/kg/day) 3

Administration Guidelines

• Give at the start of meals to minimize gastrointestinal intolerance 3

• For oral suspension, the required amount can be placed directly on the child's tongue or mixed with formula, milk, or fruit juice and given immediately 3

• Shake suspension well before each use and refrigerate after reconstitution (though not required) 3

• Discard any unused suspension after 14 days 3

Treatment Duration

• Minimum duration: Continue for 48-72 hours beyond symptom resolution or evidence of bacterial eradication 3

• Streptococcal infections: Minimum 10 days to prevent acute rheumatic fever 3

• Typical respiratory infections: 7-10 days 1

Common Pitfalls to Avoid

• Underdosing in the era of resistance: The older standard dose of 40-45 mg/kg/day may be insufficient for pneumococcal infections in areas with resistance; 90 mg/kg/day is now preferred for moderate to severe infections 1, 4

• Beta-lactamase producing organisms: If the child fails to improve on amoxicillin within 48-72 hours, consider beta-lactamase-producing H. influenzae (present in 34% of cases) and switch to amoxicillin-clavulanate 4

• Premature discontinuation: Parents must complete the full course even if symptoms improve, as clinical improvement typically occurs within 48-72 hours but bacterial eradication requires the full duration 1, 3

Monitoring for Treatment Response

• Expected improvement: Children should show clinical improvement within 48-72 hours of starting appropriate therapy 1

• If no improvement: Reevaluate for resistant organisms, incorrect diagnosis, or complications 1

• Most common adverse effects: Diarrhea, nausea, vomiting, and rash may occur 1