💊 Paracetamol (Acetaminophen) is a cheap, widely used analgesic and antipyretic with few side effects when used appropriately.
⚠️ The major concern is its potential for severe hepatotoxicity in overdose.
Fizzy dispersible 500 mg tablets are useful in patients who cannot swallow tablets, but regular use adds a high sodium load.
📖 About
- Check the BNF entry here for up-to-date prescribing advice.
- One of the most commonly used analgesics in the world, available PO, PR, and IV.
- Discovered at the University of Strasbourg in the 1880s; early recognition of its antipyretic effect by Prof. Kussmaul’s assistants.
⚙️ Mechanism of Action
- Weak anti-inflammatory action; exact mechanism not fully understood.
- Acts via indirect, reversible inhibition of COX enzymes (central rather than peripheral effect).
- Antipyretic effect: reduces hypothalamic set-point for temperature regulation.
💊 Dose
- Standard adult dose: 500 mg – 1 g every 4–6 h (maximum 4 g/day).
- Reduced dose: Half dose in adults < 50 kg or in malnutrition/frailty.
- IV formulation reserved for when oral/rectal routes are not possible (more expensive).
🎯 Indications
- Mild–moderate pain (analgesia).
- Fever (antipyretic).
- Occasional use as part of multimodal analgesia in more severe pain (with opioids/NSAIDs).
⛔ Contraindications
- Severe hepatic impairment or acute liver failure.
- Known allergy to paracetamol.
⚠️ Side Effects
- Generally well tolerated at therapeutic doses.
- Overdose: hepatotoxicity due to accumulation of toxic metabolite NAPQI (N-acetyl-p-benzoquinone imine) once glutathione stores are saturated.
- Complications: acute liver necrosis, renal failure, coagulopathy (↑ PT/INR), encephalopathy; may require liver transplant.
- Deaths are not uncommon in late-presenting overdoses.
🔄 Interactions
- Potentiates the anticoagulant effect of warfarin.
- Concurrent alcohol use ↑ risk of hepatotoxicity.
- Caution with enzyme-inducing drugs (e.g., rifampicin, carbamazepine) that may enhance toxic metabolite formation.
📚 References
