Paracetamol overdose Paediatric

These guidelines relate to paediatric patients only. Click for ADULT Paracetamol overdoses.


  • Hepatocellular necrosis is the major toxic effect
  • Biochemical evidence of maximal damage may not be attained until 72 - 96 hours after ingestion
  • Severe liver damage is defined as a peak plasma ALT exceeding 1000 u/L
  • Those who present > 12 hours post ingestion tend to be more severely poisoned and at greater risk
  • Acute renal tubular damage and necrosis may also occur
  • If there is doubt about the timing or the need for treatment - treat
  • Methionine is ineffective in patients who have been given oral activated charcoal
  • NAC is the treatment of choice when patients are vomiting or present more than 8 hours after ingestion.

Do NOT take plasma levels within 4 hours of ingestion as they are unreliable.

But patients may give inaccurate histories. If in doubt, treat with NAC.

Antidote ( NAC ) doses

We would like to move to a simpler 2 bag NAC infusion strategy but are in negotiation with our paediatric colleagues so, in the interim, please check Toxbase for NAC dosing regimes.

Specialist advice on those with liver disease.

Patients who develop severe liver damage may merit discussion with a specialist liver unit (not necessarily a liver transplant unit). Such discussions are likely to be of greater benefit if they are held early. Patients in this category include those who have an INR greater than 3.0, an elevated plasma creatinine, evidence of acidosis or encephalopathy, hypotension (mean arterial pressure less than 60 mmHg) or pre-existing liver disease.

Adverse reactions to NAC

  • N-acetylcysteine adverse effects may be localised to infusion site or be more generalised
  • Usually occur during the first 30 minutes of administration (large dose given rapidly)
  • Include nausea, flushing, itching, erythematous rashes, urticaria, angioedema, bronchospasm and, rarely, ↑BP or ↓BP
  • Infusion of NAC should be stopped and an antihistamine given
  • Once adverse effects settled, resume infusion at the lowest infusion rate (100 mg/kg over 16 hours)

Content by Dr Íomhar O' Sullivan. Last review Dr Rory O'Brien, Dr ÍOS27/11/22