What is the maximum daily dose of paracetamol (acetaminophen) for an average adult with normal liver and kidney function?

Maximum Daily Paracetamol Dose for Adults

The FDA-approved maximum daily dose of paracetamol is 4000 mg (4 grams) per 24 hours for healthy adults with normal liver and kidney function, though increasingly conservative recommendations suggest limiting chronic use to 3000 mg per day to reduce hepatotoxicity risk. 1, 2, 3

Standard Dosing Parameters

• The absolute maximum is 4000 mg per day, not to exceed 6 doses in 24 hours 1
• Each single dose should not exceed 1000 mg 4, 1
• Minimum interval between doses is 4 hours 3, 1
• Typical dosing regimen: 650-1000 mg every 4-6 hours 2, 3, 4

Conservative Dosing for Safety

For chronic daily use (beyond 10-14 days), limit to 3000 mg per day maximum to minimize hepatotoxicity risk, as recommended by the National Comprehensive Cancer Network and American College of Clinical Pharmacology. 2, 3, 4 This more conservative threshold is increasingly preferred because:

• Even therapeutic doses of 4 g/day for 14 days can cause liver enzyme elevations (ALT >3× normal) in 31-41% of healthy adults 4
• Repeated supratherapeutic ingestions (doses just above therapeutic range) carry worse prognosis than acute single overdoses, accounting for approximately 30% of acetaminophen overdose admissions 2, 3, 4

Critical Safety Warnings

You must account for ALL sources of paracetamol to avoid exceeding the daily maximum 1:

• Check all over-the-counter cold remedies, sleep aids, and combination pain relievers 2, 3
• Prescription combination products (with opioids) are now limited to ≤325 mg paracetamol per tablet 2, 3, 4
• When prescribing up to 4000 mg/day, explicitly counsel patients to avoid all other paracetamol-containing products 2, 3

Special Populations Requiring Dose Reduction

Patients with liver disease (cirrhosis or chronic liver disease): Maximum 2000-3000 mg per day 2, 3, 4

Chronic alcohol users (≥3 drinks daily): Maximum 2000-3000 mg per day, as hepatotoxicity can occur at doses ≤4000 mg in this population 3, 4

Elderly patients (≥60 years): Consider reducing maximum to 3000 mg per day, though single doses can remain 1000 mg 2, 3, 4

Hepatotoxicity Risk Thresholds

• Most acute liver failure cases occur with ingestions exceeding 10 grams per day 2
• However, severe liver injury can rarely occur at doses as low as 3-4 grams per day in patients with risk factors 2
• Serum aminotransferase levels >3500 IU/L or AST >1000 IU/L indicate severe hepatotoxicity 2, 4

Algorithm for Safe Prescribing

1. For acute pain (<10 days): Use up to 4000 mg/day maximum, ensuring patient avoids all other paracetamol sources 1
2. For chronic pain (>10-14 days): Use 3000 mg/day maximum rather than 4000 mg 2, 3, 4
3. If inadequate pain relief at 3000 mg/day: Add adjuvant analgesics (topical agents, NSAIDs, regional blocks) rather than increasing to 4000 mg 3
4. Review all medications (prescription and OTC) to identify hidden paracetamol sources 2, 3