Paracetamol and Common Drug Dosing for Adults and Pediatrics
Paracetamol (Acetaminophen) Dosing
Adult Dosing
For adults, the optimal single dose of paracetamol is 1 gram (1000 mg), with a maximum daily dose of 4 grams (4000 mg), administered every 4-6 hours. 1
- Standard adult dose: 650-1000 mg every 4-6 hours 1
- Maximum daily dose: Not to exceed 6 doses in 24 hours or 4000 mg total 1
- Timing: Doses should be spaced at least 4 hours apart 1
Critical safety warning: Severe liver damage may occur if an adult takes more than 6 doses in 24 hours, exceeds 4000 mg daily, combines paracetamol with other acetaminophen-containing products, or consumes 3 or more alcoholic drinks daily while using this medication 1.
Pediatric Dosing
For children, paracetamol should be dosed at 10-15 mg/kg every 4 hours, with a maximum daily dose of 60-75 mg/kg/day, not exceeding 4 grams per day. 2, 3, 4
Age-Based Dosing (Liquid Formulation)
- Under 2 years: Consult a doctor 1
- 2 to under 4 years: 5 mL (160 mg) every 4 hours, maximum 5 doses in 24 hours 1
- 4 to under 6 years: 7.5 mL (240 mg) every 4 hours, maximum 5 doses in 24 hours 1
- 6 to under 12 years: 10-15 mL (325 mg) every 4 hours, maximum 5 doses in 24 hours 1
- 12 years and older: 20.3 mL (650 mg) every 4-6 hours, maximum 6 doses in 24 hours 1
Weight-Based Dosing (Preferred Method)
- Single dose: 10-15 mg/kg every 4 hours 2, 3
- Maximum daily dose: 60 mg/kg/day for routine pain/fever 2, 3
- For acute severe pain: Up to 75-80 mg/kg/day may be used, though recent guidelines recommend not exceeding 75 mg/kg/day 4, 5
Important pediatric considerations: Children with pre-existing malnutrition, obesity, or neuromuscular disorders may have increased risk of hepatotoxicity and require careful monitoring 6.
Other Commonly Used Drug Dosages
Antibiotics
Amoxicillin
- Adults: 500 mg every 8 hours or 875 mg every 12 hours orally 7
- Pediatrics: 60 mg/kg/day divided into 2 doses for uncomplicated infections 5
Amoxicillin-Clavulanate
- Adults: 875/125 mg twice daily orally 7
- Pediatrics: Dosed based on amoxicillin component, typically 45 mg/kg/day divided twice daily 7
Azithromycin
- Adults: 500 mg on day 1, then 250 mg daily for 4 days 8
- Pediatrics: 10 mg/kg on day 1 (maximum 500 mg), then 5 mg/kg daily for 4 days (maximum 250 mg) 8
Cephalexin
Antihistamines
Diphenhydramine
- Adults: 25-50 mg every 4-6 hours, maximum 300 mg/day 9
- Pediatrics: 1-2 mg/kg/dose every 4-6 hours, maximum 300 mg/day 9
Analgesics
Ibuprofen
- Adults: 400-600 mg every 6-8 hours, maximum 2400 mg/day 6
- Pediatrics: 5-10 mg/kg/dose every 6-8 hours, maximum 40 mg/kg/day (not exceeding 2400 mg/day) 6
Caution: NSAIDs should be avoided in children with dehydration, renal impairment, or nephrotic syndrome relapses 6.
Antiemetics
Ondansetron
Antitussives/Expectorants
Guaifenesin/Dextromethorphan
- Adults: Dosing varies by formulation; follow product-specific guidelines 10
- Pediatrics: Age and weight-based dosing with 15% rounding tolerance acceptable 10
Key Prescribing Principles
When prescribing for children, always include on the prescription: the daily dose, number of divided doses, duration of therapy, indication, and the child's weight 5. This reduces medication errors and unnecessary pharmacist consultations.
For medications with narrow therapeutic indices (digoxin, calcitriol, morphine), do not round doses 10. For medications with wider therapeutic windows (penicillin, guaifenesin), rounding by 10-15% is acceptable to facilitate home administration 10.
Special populations requiring dose adjustment:
- Elderly patients (≥65 years): May require reduced doses of certain medications due to declining renal function 11
- Patients with hepatic insufficiency: Paracetamol is contraindicated in decompensated liver disease 2, 12
- Patients with renal impairment: Dose adjustments needed for renally cleared medications 12