What is the recommended dosage of paracetamol (acetaminophen) for adults?

Adult Paracetamol (Acetaminophen) Dosage

For adults, the standard dose of paracetamol is 650-1000 mg every 4-6 hours, with a maximum single dose of 1000 mg and a maximum daily dose not exceeding 4000 mg (4 grams) in 24 hours. 1, 2, 3

Standard Dosing Regimen

• Single dose: 650-1000 mg every 4-6 hours 1, 3
• Maximum single dose: 1000 mg (1 gram) 2
• Maximum daily dose: 4000 mg (4 grams) in 24 hours 1, 2, 3
• Maximum number of doses: Not to exceed 6 doses in 24 hours 3

The FDA-approved labeling specifies that adults should take 650 mg (20.3 mL of liquid formulation) every 4-6 hours, not exceeding 6 doses in 24 hours. 3

Conservative Dosing Recommendations

A more conservative maximum daily limit of 3000-3250 mg is increasingly recommended to reduce hepatotoxicity risk, particularly for chronic use. 1

• Multiple guidelines now suggest limiting chronic administration to 3 grams or less per day due to safety concerns 4, 1
• The optimum unit dose for analgesic efficacy in adults is 1 gram 5
• Analgesic activity typically lasts approximately 6 hours 5

Special Populations Requiring Dose Adjustment

Liver Disease

• Patients with cirrhosis or chronic liver disease: Reduce maximum daily dose to 2-3 grams (2000-3000 mg) 1
• Hepatic insufficiency: Paracetamol is contraindicated in decompensated hepatic insufficiency 5, 6
• Chronic alcohol users have developed hepatic failure at doses ≤4 grams, though evidence is mixed 1

Elderly Patients

• No routine dose reduction is required for older adults 6, 7
• However, some guidelines suggest considering a maximum of 3000 mg daily for patients ≥60 years due to decreased metabolism 1, 2
• Dosing should be individualized for frail elderly patients in consultation with their physician 6

Renal Disease

• No routine dose reduction is necessary for chronic renal insufficiency, even though clearance is reduced 5
• For advanced kidney failure, dosing should be individualized 6

Critical Safety Warnings

Hepatotoxicity Risk

Severe liver damage may occur if an adult takes more than 6 doses in 24 hours or exceeds 4000 mg daily. 3

• Repeated supratherapeutic ingestions (doses just above therapeutic range) can result in hepatotoxicity, hepatic failure, and death 1, 2
• Doses ranging from just over 4 grams per day to greater than 15 grams per day have been associated with liver damage 1, 2
• Approximately 30,000 patients are hospitalized annually in the US for acetaminophen toxicity 8

Combination Product Hazards

Never use paracetamol with any other drug containing acetaminophen (prescription or nonprescription). 3

• The FDA has limited acetaminophen content in prescription combination products to ≤325 mg per dosage unit to reduce overdose risk 4, 1, 2
• Up to half of acetaminophen overdoses are unintentional, largely related to opioid-acetaminophen combinations 8
• Approximately 6% of adults are prescribed acetaminophen doses exceeding 4 grams daily, often inadvertently 8

Alcohol Interaction

• Avoid taking paracetamol with 3 or more alcoholic drinks daily while using this product 3
• Chronic alcohol users are at increased risk of hepatotoxicity even at therapeutic doses 1

Common Prescribing Pitfalls

The most dangerous errors involve failing to recognize acetaminophen in combination products, leading to unintentional overdose. 1

• Using multiple acetaminophen-containing products simultaneously (cold medicines, sleep aids, pain relievers) without tracking total daily intake 1, 2
• Not adjusting dosage for patients with liver disease or chronic alcohol use 1
• Exceeding recommended dosing frequency by taking doses too close together 1
• Prescribing combination opioid-acetaminophen products without counseling patients about additional acetaminophen use 4

Clinical Context for Pain Management

Paracetamol is recommended as a first-line agent for:

• Mild pain (pain intensity 1-4 on numeric rating scale) 4
• Osteoarthritis pain, with regular dosing often needed 4
• Musculoskeletal pain, where it has fewer side effects than NSAIDs 4
• Cancer pain as part of the WHO analgesic ladder for mild pain 4

For moderate pain (intensity 5-7), paracetamol may be combined with weak opioids or NSAIDs, but careful attention must be paid to total acetaminophen content in combination products. 4