What is the recommended dosage of paracetamol (acetaminophen) for adults and children, and what are the contraindications and precautions?

Paracetamol (Acetaminophen) Dosing and Safety Guidelines

Adult Dosing

For adults, the standard dose is 650–1000 mg every 4–6 hours, with a maximum daily limit of 4000 mg (4 grams) in healthy individuals under 60 years, though a more conservative limit of 3000 mg is increasingly recommended to reduce hepatotoxicity risk. 1, 2

Standard Adult Dosing (Under 60 Years)

• 650–1000 mg every 4–6 hours 1
• Maximum 6 doses in 24 hours 1
• Do not exceed 4000 mg per day (FDA-approved maximum) 1, 3
• Conservative recommendation: limit to 3000–3250 mg daily for chronic use to minimize liver injury risk 2, 3

Elderly Patients (≥60 Years)

• Maximum daily dose should be reduced to 3000 mg (3 grams) per day 2, 3
• Use the same per-dose amount (650–1000 mg) but with stricter daily limits 2
• Scheduled dosing every 6 hours (e.g., 650–1000 mg) is more effective than as-needed dosing for consistent pain control 2

High-Risk Populations Requiring Dose Reduction

• Patients with liver cirrhosis or chronic liver disease: 2000–3000 mg maximum daily 3
• Chronic alcohol users: 2000–3000 mg maximum daily due to increased hepatotoxicity risk at doses as low as 4–5 grams 3
• Patients with decompensated cirrhosis or advanced liver disease require individualized dosing in consultation with their physician 4

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Pediatric Dosing

For children, paracetamol should be dosed at 10–15 mg/kg every 4–6 hours, with a maximum of 5 doses in 24 hours and a total daily dose not exceeding 60–75 mg/kg/day. 5, 6

Weight-Based Dosing

• 15 mg/kg per dose is optimal for efficacy in fever and pain management 6
• Administer every 4–6 hours as needed 5, 6
• Maximum 5 doses in 24 hours 1
• Total daily dose should not exceed 60–75 mg/kg/day 5

Age-Based Dosing (FDA Label)

• Children 2 to under 4 years: 160 mg (5 mL) every 4 hours, maximum 5 doses/24 hours 1
• Children 4 to under 6 years: 240 mg (7.5 mL) every 4 hours, maximum 5 doses/24 hours 1
• Children 6 to under 12 years: 325 mg (10.15 mL) every 4 hours, maximum 5 doses/24 hours 1
• Children 12 years and older: adult dosing (650 mg every 4–6 hours, maximum 6 doses/24 hours) 1
• Children under 2 years: consult a doctor 1

Pediatric Safety Profile

• Paracetamol 15 mg/kg has a tolerability profile similar to placebo and is safer than NSAIDs for consecutive-day use 6
• Unlike NSAIDs, paracetamol is indicated for use in children of all ages 6
• Single ingestions exceeding 140–150 mg/kg are potentially toxic 5

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Contraindications and Precautions

Absolute Contraindications

• Known allergy to acetaminophen 1
• Severe skin reactions (skin reddening, blisters, rash) from prior acetaminophen use 1

Critical Warnings and Precautions

Hepatotoxicity Risk

• Severe liver damage may occur if an adult takes more than 6 doses in 24 hours or exceeds 4000 mg daily 1
• Do not use in patients with active liver disease without dose adjustment 1
• Chronic alcohol users (≥3 drinks daily) are at increased risk of liver damage even at therapeutic doses 1, 3
• Repeated supratherapeutic ingestions (doses just above therapeutic range) account for 30% of acetaminophen overdose admissions, with 15% progressing to severe hepatotoxicity 3

Drug Interactions

• Do not use with any other drug containing acetaminophen (prescription or nonprescription) 1
• Ask a doctor or pharmacist before use if taking warfarin 1
• Check all medications including OTC cold remedies, sleep aids, and opioid combinations for hidden acetaminophen content 2, 3
• Fixed-dose opioid/acetaminophen products should contain ≤325 mg acetaminophen per unit to prevent unintentional overdose 3

Duration Limits

• Do not use for more than 10 days for pain unless directed by a doctor 1
• Do not use for more than 3 days for fever unless directed by a doctor 1
• For chronic pain under physician supervision, use ≤3000 mg/day rather than the 4000 mg maximum 3
• Monitor liver enzymes (AST/ALT) regularly if therapy extends beyond 7–10 days at near-maximum doses 2, 3

Special Populations

• Pregnant or breastfeeding women: ask a health professional before use 1
• Elderly patients have normal pharmacokinetics and do not require routine dose reduction based on age alone, but the 3000 mg daily maximum is recommended for safety 2, 4
• Patients with advanced kidney failure should have dosing individualized in consultation with their physician 4

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Clinical Advantages and First-Line Status

Paracetamol is recommended as first-line therapy for mild to moderate pain in adults and children due to its superior safety profile compared to NSAIDs and opioids. 7, 2

Advantages Over NSAIDs

• Provides pain relief comparable to NSAIDs without gastrointestinal bleeding risk 7
• No adverse renal effects, cardiovascular toxicity, or platelet dysfunction 7, 2
• Safe in patients with chronic kidney disease, heart failure, cardiovascular disease, and aspirin-sensitive asthma 4, 8

Advantages Over Opioids

• Avoids risks of respiratory depression, constipation, cognitive impairment, falls, and addiction 2
• Particularly important in elderly patients who are vulnerable to opioid-related adverse events 2

Guideline Recommendations

• American Geriatrics Society: acetaminophen is the preferred first-line pharmacologic treatment for mild to moderate osteoarthritis pain 7
• NICE guidelines: offer paracetamol for pain relief as first-line therapy before NSAIDs or opioids 7
• Clinical Microbiology and Infection: paracetamol and ibuprofen are more effective than placebo for acute sore throat, with paracetamol being the safest option 7

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Common Pitfalls to Avoid

Unintentional Overdose

• Failing to recognize acetaminophen in combination products (cold medicines, sleep aids, opioid combinations) leading to exceeding the daily maximum 3
• Using multiple acetaminophen-containing products simultaneously without tracking total daily intake 3
• Prescribing combination opioid products without accounting for their acetaminophen content toward the daily limit 2

Inadequate Dosing

• Using subtherapeutic doses ≤10 mg/kg in children, which are less effective than NSAIDs; use 15 mg/kg for optimal efficacy 6
• As-needed dosing instead of scheduled dosing, which results in inconsistent pain control; scheduled every-6-hour dosing is superior 2

Risk Factor Oversight

• Not adjusting dosage for patients with liver disease, chronic alcohol use, or age ≥60 years 2, 3
• Failing to counsel patients explicitly to avoid all other acetaminophen-containing products when prescribing up to the daily maximum 2, 3

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Overdose Management

Recognition and Initial Treatment

• Administer activated charcoal 1 g/kg orally immediately if patient presents within 4 hours of ingestion 3
• Begin N-acetylcysteine (NAC) promptly when serum acetaminophen level is above the treatment line, aminotransferases are rising, or reported ingestion exceeds safe limits 3

NAC Dosing Protocol

• Loading dose: 150 mg/kg IV over 15 minutes 3
• Maintenance Part 1: 50 mg/kg IV over 4 hours 3
• Maintenance Part 2: 100 mg/kg IV over 16 hours 3

Critical Considerations

• Quick medical attention is critical even if no signs or symptoms are present 1
• Contact Poison Control Center (1-800-222-1222) immediately 1
• Most acute liver failure occurs with ingestions exceeding 10 grams, though severe injury can rarely occur at 3–4 grams in high-risk patients 3