Clinical presentation

Accidental ingestion of small amounts (eg one mouthful or 5 to 10 mL) of a hydrocarbon substance (excluding essential oils) may not cause any symptoms or only cause mild central nervous system (CNS) effects. This commonly occurs in adults siphoning petrol.

Effects of hydrocarbon ingestion may include:

• CNS effects—euphoria, drowsiness, ataxia, irritability, agitation, coma, seizures (primarily in children); onset of CNS effects occur within one hour
• respiratory effects
  • transient choking and coughing
  • aspiration pneumonitis that presents with cough, dyspnoea, increased respiratory effort, wheeze, cyanosis; onset of effects occurs within 4 to 6 hours, but it can take up to 24 hours for effects to peak
  • acute respiratory distress syndrome
• gastrointestinal effects
  • nausea, vomiting, reflux, hydrocarbon-smelling diarrhoea resulting in perineal excoriation and burns (especially after kerosene ingestion in children and comatose patients)
  • acute liver injury—benzene, carbon tetrachloride, chloroform
• cardiovascular effects—hypotension.

Methylene chloride poisoning causes typical hydrocarbon toxic effects as above, but additionally, it causes carbon monoxide poisoning when it is metabolised in the body. Raised carboxyhaemoglobin fraction displaces oxygen from haemoglobin and causes hypoxia affecting any organ.