Acetaminophen

What it is used for

Acetaminophen injection is used for the management of mild to moderate pain in adults and children 2 years and older, the management of moderate to severe pain with adjunctive opioid analgesics in adults and children 2 years and older, and the reduction of fever in adults and children.

How it is taken

Acetaminophen injection is given as a 15-minute intravenous infusion. Dosing depends on age and weight. For adults and adolescents weighing 50 kg or more, the usual dose is 1000 mg every 6 hours or 650 mg every 4 hours, with a maximum of 4000 mg per day. For those weighing less than 50 kg, the dose is based on weight. For children 2 to 12 years, the dose is 15 mg/kg every 6 hours or 12.5 mg/kg every 4 hours. For neonates and infants, specific weight-based dosing is used. Do not exceed the maximum daily dose.

Warnings

• WARNING: Risk of medication errors and hepatotoxicity. Dosing errors can lead to accidental overdose and death.
• Acetaminophen can cause acute liver failure, sometimes requiring liver transplant or resulting in death, especially when doses exceed the maximum daily limits.
• Ensure the total daily dose of acetaminophen from all products does not exceed the maximum recommended dose.
• Serious skin reactions and allergic/hypersensitivity reactions may occur.

Common side effects

• In adults: nausea, vomiting, headache, insomnia.
• In pediatric patients: nausea, vomiting, constipation, itching (pruritus).

Interactions

Substances that affect the liver enzyme CYP2E1 may alter acetaminophen metabolism and increase the risk of liver damage. Chronic use of high-dose acetaminophen (4000 mg/day) may increase INR in patients on warfarin. More frequent INR monitoring may be needed if using acetaminophen injection with oral anticoagulants.