What is the dose for intravenous (IV) acetaminophen?

IV Acetaminophen Dosing Guidelines

The recommended dose for IV acetaminophen in adults is 1000 mg every 6 hours or 650 mg every 4 hours, with a maximum daily dose of 4000 mg. 1

Adult Dosing

Standard Adult Dosing (≥50 kg):

• 1000 mg every 6 hours OR
• 650 mg every 4 hours
• Maximum single dose: 1000 mg
• Minimum dosing interval: 4 hours
• Maximum daily dose: 4000 mg (includes all routes of administration and all acetaminophen-containing products) 1

Adults Weighing <50 kg:

• 15 mg/kg every 6 hours OR
• 12.5 mg/kg every 4 hours
• Maximum single dose: 15 mg/kg
• Maximum daily dose: 75 mg/kg/day 1

Pediatric Dosing

Children (2-12 years):

• 15 mg/kg every 6 hours OR
• 12.5 mg/kg every 4 hours
• Maximum single dose: 15 mg/kg
• Maximum daily dose: 75 mg/kg/day 1

Neonates (≤28 days, ≥32 weeks gestational age):

• 12.5 mg/kg every 6 hours
• Maximum daily dose: 50 mg/kg/day
• Minimum dosing interval: 6 hours 1

Infants (29 days to 2 years):

• 15 mg/kg every 6 hours
• Maximum daily dose: 60 mg/kg/day
• Minimum dosing interval: 6 hours 1

Administration Guidelines

• Administer IV acetaminophen as a 15-minute infusion 1
• For 1000 mg doses in adults ≥50 kg: administer directly from the 100 mL vial
• For doses <1000 mg: withdraw appropriate dose and place in a separate sterile container prior to administration 1
• For pediatric doses up to 60 mL: place in a syringe and administer over 15 minutes using a syringe pump 1
• Once the container seal has been penetrated or contents transferred, administer within 6 hours 1

Clinical Considerations

Efficacy

• IV acetaminophen is effective for mild to moderate pain management and as an adjunct to opioids for moderate to severe pain 1
• When used as an adjunct to opioids in critically ill adults, IV acetaminophen decreases pain intensity and reduces opioid consumption 2
• In post-surgical patients, IV acetaminophen has been associated with improved time to extubation, reduced sedation, and decreased nausea rates 2

Safety Considerations

• Monitor for IV acetaminophen-associated hypotension, which may occur in up to 50% of patients (decrease in mean arterial pressure >15 mmHg) 2
• Calculate maximum daily dose based on all routes of administration and all acetaminophen-containing products 1
• Use with caution in patients with hepatic impairment, alcoholism, chronic malnutrition, severe hypovolemia, or severe renal impairment 1
• Contraindicated in patients with severe hepatic impairment or severe active liver disease 1

Special Populations

• In critically ill patients, standard dosing may result in serum concentrations below the therapeutic range due to increased elimination 3
• For elderly patients, dose adjustment is not typically necessary, though starting with lower doses may be prudent 4
• In patients with liver disease, a more conservative maximum daily dose of 2000-3000 mg is recommended 4

Practical Application

• IV acetaminophen is particularly beneficial in patients at higher risk for opioid-associated adverse effects (e.g., patients recovering from abdominal surgery at risk for ileus, nausea, or vomiting) 2
• Do not add other medications to the acetaminophen IV solution; diazepam and chlorpromazine are physically incompatible with IV acetaminophen 1
• Monitor the end of the infusion to prevent air embolism, especially when IV acetaminophen is the primary infusion 1

Remember that exceeding the recommended maximum daily dose may result in hepatic injury, including liver failure and death 1. Always calculate the total acetaminophen dose from all sources to avoid inadvertent overdose.