Paracetamol (Acetaminophen) Dosing for Adults
For healthy adults, the standard dose is 650-1000 mg every 4-6 hours, with a minimum 4-hour interval between doses, not exceeding 6 doses in 24 hours or a maximum daily limit of 4000 mg. 1, 2
Standard Dosing Parameters
- The typical regimen is 650-1000 mg every 4-6 hours, with the maximum single dose being 1000 mg 1, 3
- The minimum interval between doses is 4 hours, and patients should not exceed 6 doses in 24 hours 1, 2
- The FDA-approved maximum daily dose is 4000 mg per 24 hours for healthy adults 4, 3, 2
Conservative Dosing for Chronic Use
For chronic daily use, limit acetaminophen to 3000 mg per day rather than 4000 mg to minimize hepatotoxicity risk. 1, 4, 3
- The National Comprehensive Cancer Network recommends this 3000 mg daily maximum for long-term administration 1, 4
- Repeated supratherapeutic ingestions (doses just above therapeutic range) carry worse prognosis than acute single overdoses, accounting for approximately 30% of acetaminophen overdose admissions 1, 4
- Even therapeutic doses of 4 g/day for 14 days can cause ALT elevations >3× normal in 31-41% of healthy adults 3
High-Risk Populations Requiring Dose Reduction
Elderly patients (≥60 years): Maximum daily dose should be reduced to 3000 mg per day, with starting doses at the lower end of the range (325 mg per dose for frail elderly) 5, 1, 3
Patients with liver disease or cirrhosis: Limit to 2000-3000 mg daily maximum 1, 4, 3
Chronic alcohol users: Maximum daily dose should be limited to 2000-3000 mg per day, as hepatotoxicity can occur at doses ≤4000 mg in this population 1, 3
Critical Safety Warnings
When prescribing up to 4000 mg/day, explicitly counsel patients to avoid ALL other acetaminophen-containing products, including: 1, 4
- Over-the-counter cold remedies and sleep aids
- Prescription opioid combination products
- Any other medications containing acetaminophen
Common pitfalls leading to unintentional overdose: 4
Failing to recognize acetaminophen in combination products
Using multiple acetaminophen-containing products simultaneously without tracking cumulative dose
Not adjusting dosage for patients with liver disease or chronic alcohol use
Prescription combination products are FDA-mandated to contain ≤325 mg acetaminophen per dosage unit 1, 4, 3
Multimodal Approach for Inadequate Pain Relief
Rather than exceeding 3000 mg daily, add adjuvant therapies when acetaminophen alone provides insufficient pain control: 1
- Topical lidocaine patches
- Regional nerve blocks
- NSAIDs (with appropriate precautions)
- Low-dose opioids if indicated