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Analgesic / Antipyretic Pregnancy: B — safe in all trimesters

Paracetamol

Brand names: Panadol, Calpol, Perfalgan (IV)

Adult dose

Dose: 500mg–1g every 4–6 hours
Route: Oral, IV, PR
Frequency: Every 4–6 hours
Max 4g/24h. IV Perfalgan: 1g over 15min. Reduce max to 2g/24h in hepatic impairment, malnutrition, or weight <50kg.

Paediatric dose

Dose: 15 mg/kg
Route: Oral or IV
Frequency: Every 4–6 hours
Max: 1000mg per dose
Max 60mg/kg/day (oral/PR) or 75mg/kg/day (IV). Neonates: 10mg/kg/dose.
Paediatric weight-based calculator

Max 60mg/kg/day (oral/PR) or 75mg/kg/day (IV). Neonates: 10mg/kg/dose.

Clinical pearls

  • Overdose: N-acetylcysteine within 8–10h of ingestion is most effective; use treatment nomogram
  • Safe in renal impairment (preferred over NSAIDs)
  • Regular paracetamol may increase INR in warfarin patients — monitor carefully
  • Weight-based dosing essential in children — use Calpol weight bands

Contraindications

  • Hepatic failure
  • Known hypersensitivity

Side effects

  • Hepatotoxicity (overdose)
  • Thrombocytopenia (rare)
  • Rash (rare)

Interactions

  • Warfarin — regular high doses increase INR (monitor)
  • Isoniazid — increased hepatotoxicity risk
  • Carbamazepine — increased hepatotoxicity risk

Monitoring

  • LFTs and INR in overdose
  • INR if concurrent warfarin use

Reference: BNFc; BNF; MHRA Paracetamol Overdose Guidelines. Verify against your local formulary and the latest BNF before prescribing.

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