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

Paracetamol's Mechanism of Action in Treating Fever

Paracetamol (acetaminophen) reduces fever by inhibiting prostaglandin synthesis in the central nervous system, particularly in the hypothalamus, which is the body's temperature regulation center. The recommended dosage for adults is 1000 mg per dose, not exceeding 4000 mg in a 24-hour period.

Mechanism of Action

• Paracetamol works primarily by inhibiting cyclooxygenase (COX) enzymes in the central nervous system, which reduces prostaglandin synthesis in the hypothalamus 1
• Unlike NSAIDs, paracetamol has minimal peripheral anti-inflammatory effects, which explains its efficacy for fever with fewer side effects 2
• Paracetamol should be used to treat fever when it causes discomfort, not solely to reduce body temperature 1

Recommended Dosing for Adults

• The maximum single dose for adults is 1000 mg (1 gram) 3, 4
• The maximum daily dose should not exceed 4000 mg (4 grams) in a 24-hour period 3, 4
• For elderly patients (≥60 years), some guidelines suggest reducing the maximum daily dose to 3000 mg, though the single dose maximum remains 1000 mg 3

Clinical Efficacy

• Paracetamol begins to reduce fever within 30-60 minutes after administration 5
• The antipyretic effect typically lasts for 4-6 hours, requiring repeated dosing for continued fever management 2
• Effervescent tablets may provide more rapid absorption and onset of action compared to conventional tablets 2
• Recent evidence shows that when used at appropriate doses, paracetamol is significantly more effective than placebo and at least as effective as NSAIDs for fever management 6

Safety Considerations

• Paracetamol has a better safety profile than NSAIDs, making it the first-line therapy for fever 1
• Unlike NSAIDs, paracetamol is not associated with significant gastrointestinal bleeding, adverse renal effects, or cardiovascular toxicity 1
• Exceeding the recommended maximum dose can lead to severe hepatotoxicity, liver failure, and potentially death 3, 4
• Patients should be cautious about taking multiple acetaminophen-containing products simultaneously to avoid unintentional overdose 4

Special Situations

• In patients with intracerebral hemorrhage, treating elevated temperature with paracetamol may be reasonable to improve functional outcomes 1
• For patients with cancer pain, paracetamol is often used as a first-line agent before moving to stronger medications 1
• Paracetamol can be safely used in patients with chronic renal insufficiency without dose adjustment 2
• Paracetamol is contraindicated in patients with hepatic insufficiency 2

Warning Signs of Toxicity

• Early signs of paracetamol toxicity include nausea, vomiting, and abdominal pain 3
• Elevated liver enzymes (AST/ALT) may indicate developing hepatotoxicity, particularly in cases of repeated supratherapeutic ingestion 3
• Severe skin reactions may occur, including reddening, blisters, and rash 4

Paracetamol remains the safest and most effective first-line antipyretic for most patients when used at appropriate doses. Its central mechanism of action provides effective fever reduction with minimal peripheral side effects compared to NSAIDs.