Paracetamol Overdose

Question 1

Definition

Answer 1

Excessive ingestion of paracetamol causing toxicity

Question 2

Aetiology

Answer 2

· MAX recommended dose: 2 x 500 mg tablets, 4 x in 24 hrs

· Intake > 12 g can cause hepatic necrosis

Question 3

Risk factors

Answer 3

o Chronic alcohol abusers
o Patients on enzyme-inducing drugs (e.g. anticonvulsants)
o Malnourished
o Anorexia nervosa
o HIV
o Paracetamol overdose is commonly associated with ingestion of large amounts of alcohol

Question 4

Epidemiology

Answer 4

· Most COMMON intentional drug overdose in the UK

· Causes 100 deaths/yr in the UK

Question 5

Presenting symptoms

Answer 5

· IMPORTANT: make sure you ascertain the TIMING and QUANTITY of overdose and presence of risk factors

· 0-24 hrs
o ASYMPTOMATIC
o Mild nausea/vomiting
o Lethargy
o Malaise

· 24-72 hrs
o RUQ pain
o Vomiting

· 72+ hrs
o Increased confusion (encephalopathy)
o Jaundice

Question 6

Signs on physical examination

Answer 6

· 0-24 hrs - no signs

· 24-72 hrs - liver enlargement and tenderness

· 72+ hrs - jaundice, coagulopathy, hypoglycaemia, renal angle tenderness

Question 7

Investigations

Answer 7

· Measure paracetamol levels
o NOTE: peak paracetamol levels are 4 hrs after ingestion

· Others: FBC, U&Es, Glucose, LFTs, Clotting Screen, Lactate and ABG