Maximum Oral Dose of Paracetamol in 24 Hours
The maximum oral dose of paracetamol for a healthy adult is 4000 mg per 24 hours, as mandated by the FDA, though a more conservative limit of 3000 mg per day is recommended for chronic use to reduce hepatotoxicity risk. 1, 2, 3
Standard Dosing Parameters
- The FDA-approved maximum is 4000 mg per 24 hours for healthy adults, with a maximum single dose of 1000 mg. 1, 3
- The typical dosing regimen is 650-1000 mg every 4-6 hours, with a minimum interval of 4 hours between doses and a maximum of 6 doses in 24 hours. 2, 3
- For chronic daily use (beyond 14 days), limit the dose to 3000 mg per day to minimize hepatotoxicity risk. 2, 3
Critical Safety Warnings
Severe liver damage may occur if an adult takes more than 6 doses in 24 hours or exceeds 4000 mg of paracetamol. 1
- When prescribing up to 4000 mg/day, explicitly counsel patients to avoid all other paracetamol-containing products including over-the-counter cold remedies, sleep aids, and opioid combination products. 2, 3
- Prescription combination products are limited to ≤325 mg paracetamol per dosage unit by FDA mandate. 2, 3
- Repeated supratherapeutic ingestions (doses just above therapeutic range) carry a worse prognosis than acute single overdoses, accounting for approximately 30% of paracetamol overdose admissions. 2, 3
Dose Reductions for High-Risk Populations
Elderly patients (≥60 years):
- Reduce maximum daily dose to 3000 mg per day or less. 2, 4
- For frail elderly, start at the lower end of the dosing range (325 mg per dose). 2, 4
Patients with liver disease:
- Maximum daily dose is 2000-3000 mg per day. 2, 3
- Paracetamol is contraindicated in patients with hepatic insufficiency or decompensated cirrhosis. 5, 4
Chronic alcohol users:
- Limit maximum daily dose to 2000-3000 mg per day. 2, 3
- Hepatotoxicity can occur at doses ≤4000 mg in chronic alcohol users, with severe liver damage reported at doses as low as 5-8.75 g/day. 3
- Advise patients to avoid concurrent alcohol use (3 or more alcoholic drinks daily). 1, 3
Important Clinical Context
Even therapeutic doses of 4 g/day for 14 days can cause ALT elevations >3× normal in 31-41% of healthy adults, indicating subclinical hepatotoxicity risk. 3
- Scheduled dosing every 6 hours provides superior pain control compared to as-needed administration. 4
- When paracetamol alone provides insufficient pain relief, add adjuvant therapies (topical lidocaine patches, regional nerve blocks, NSAIDs) rather than exceeding the 3000 mg daily maximum. 2, 4
- In critically ill adults, 1 gram every 6 hours (IV, oral, or rectal) is recommended as an adjunct to opioids, though IV paracetamol may cause hypotension in up to 50% of patients. 2, 3