What is the recommended dosage and usage of paracetamol (acetaminophen) for pain management and fever reduction?

Paracetamol (Acetaminophen) Dosing and Usage

For adults, paracetamol should be dosed at 650-1000 mg every 4-6 hours with a maximum of 4000 mg per 24 hours, though a more conservative limit of 3000 mg daily is increasingly recommended for chronic use to minimize hepatotoxicity risk. 1, 2, 3

Standard Adult Dosing

• The optimal single dose is 1000 mg, with dosing intervals of 4-6 hours, not exceeding 6 doses in 24 hours 4, 5
• The FDA-approved maximum daily dose is 4000 mg (4 grams) per 24 hours for healthy adults 1, 2, 3, 4
• For chronic daily use, limit to 3000 mg per day maximum to reduce hepatotoxicity risk 1, 2, 3
• Onset of action occurs within 15-30 minutes, with analgesic effect lasting approximately 6 hours 1, 5

Pediatric Dosing

• Oral dosing: 10-15 mg/kg every 4-6 hours, maximum 60 mg/kg/day 1, 5, 6
• Intravenous loading dose: 15-20 mg/kg, followed by maintenance dosing of 10-15 mg/kg every 6-8 hours 1
• Rectal loading dose: 20-40 mg/kg (15 mg/kg if <10 kg) due to poor bioavailability 1
• Children under 2 years require physician consultation before use 4

High-Risk Populations Requiring Dose Reduction

Liver Disease

• Patients with cirrhosis or chronic liver disease should limit intake to 2000-3000 mg daily maximum 7, 1, 2, 3
• Chronic alcohol users are at increased risk of hepatotoxicity even at doses ≤4000 mg, with severe liver damage reported at doses as low as 5-8.75 g/day 3
• Monitor liver enzymes (AST/ALT) regularly in patients with liver disease 1

Elderly Patients

• Start with 650 mg every 4-6 hours rather than 1000 mg in older adults 7, 1
• No routine dose reduction is required based solely on age, though individualized assessment is prudent for those ≥60 years 3, 8

Renal Impairment

• Paracetamol is the non-opioid analgesic of choice in chronic renal insufficiency 5, 8
• Dosage reduction is usually not necessary despite reduced clearance 5

Intravenous Administration for Acute Pain

• For acute abdominal pain or postoperative pain, administer 1 gram IV every 6 hours as part of multimodal analgesia 1
• IV paracetamol ensures predictable plasma concentrations when oral absorption is unreliable due to ileus or altered gastric emptying 1
• Combine with NSAIDs (ibuprofen 600-800 mg IV every 6 hours) when not contraindicated for superior analgesia 1
• Reserve opioids strictly for rescue analgesia to minimize opioid-related complications 1
• Caution: IV paracetamol may cause hypotension in hemodynamically unstable patients 3

Critical Safety Considerations

Maximum Dose Warnings

• Severe liver damage may occur if an adult takes more than 6 doses in 24 hours or exceeds 4000 mg daily 4
• Repeated supratherapeutic ingestions (doses just above therapeutic range) carry a worse prognosis than acute single overdoses, accounting for approximately 30% of overdose admissions 7, 1, 2, 3
• Even therapeutic doses of 4 g/day for 14 days can cause ALT elevations >3× normal in 31-41% of healthy adults 3

Combination Products

• When prescribing paracetamol, explicitly counsel patients to avoid all other acetaminophen-containing products including OTC cold remedies, sleep aids, and opioid combinations 1, 2
• Prescription combination products should contain ≤325 mg acetaminophen per dosage unit 2, 3

Alcohol Interaction

• Avoid taking paracetamol with 3 or more alcoholic drinks daily 4
• Chronic alcohol users have developed hepatic failure at doses ≤4 g, though evidence is mixed 3

Common Pitfalls to Avoid

• Failing to recognize paracetamol in combination products, leading to unintentional overdose 1, 2
• Using multiple acetaminophen-containing products simultaneously without tracking total daily intake 1, 2
• Not adjusting dosage for patients with liver disease or chronic alcohol use 1, 2
• Exceeding recommended dosing frequency by taking doses too close together 2
• Premature opioid escalation before optimizing non-opioid analgesics 1

Multimodal Analgesia Approach

• For mild pain (WHO Level I), use paracetamol as first-line monotherapy 1
• For moderate pain (WHO Level II), combine paracetamol with weak opioids (codeine, tramadol) 1
• For severe pain (WHO Level III), continue paracetamol with strong opioids as it provides significant additive analgesic effect 1, 6
• When combined with NSAIDs, paracetamol enhances analgesic effect or allows lower doses of each agent 7, 5, 9

Monitoring for Extended Use

• For chronic pain management under physician care, use 3 g/day or less rather than the 4 g maximum 2
• Monitor liver enzymes regularly when paracetamol is used chronically, especially at doses approaching 4 g/day 2
• Reassess need for continued paracetamol frequently and reduce dose when appropriate 2
• If inadequate pain relief at 3 g/day, add adjuvant analgesics rather than increasing to 4 g/day 2

Overdose Management

• In case of overdose, seek immediate medical attention or contact Poison Control (1-800-222-1222) 4
• Quick medical attention is critical even without obvious signs or symptoms 4
• Hepatotoxicity is defined as any AST increase; severe hepatotoxicity as AST >1000 IU/L 7, 2
• N-acetylcysteine (NAC) is the specific antidote for paracetamol overdose 7