Methane toxicity


  • Simple asphyxiant
    • Inert gases that displace oxygen and decrease FiO2
  • Lighter than air
  • Explosive
  • Natural production by bacteria in GI tract of humans, other animals

Clinical Features


  • Confined space, particularly at work
    • Mining
    • Large scale animal farming
    • Fossil fuel industry
    • Organic decomposition
  • Other people exposed may have similar symptoms


  • Wide range, nonspecific
    • Tachycardia
    • Tachypnea
    • Headache
    • Confusion
    • Nausea/vomiting
    • LOC
    • Coma
    • Cardiac arrest

Differential Diagnosis

Toxic gas exposure



  • Oxygen saturation - decreased, should improve with removal from exposure
  • No definitive test for methane
  • Consider other diagnostic testing to rule out other causes if unsure exposure or lack of improvement:


  • Clinical/diagnosis of exclusion
    • Often based on history of exposure


  • Supplemental oxygen
  • Other supportive care as indicated


  • Discharge
    • If stable vitals, improved mental status, and otherwise asymptomatic
  • Admit
    • If needed for further supportive care

See Also

External Links


  • Kuschner WG, Blanc PD. Kuschner W.G., & Blanc P.D. Kuschner, Ware G., and Paul D. Blanc.Gases & Other Airborne Toxicants. In: LaDou J, Harrison RJ. LaDou J, & Harrison R.J.(Eds.),Eds. Joseph LaDou, and Robert J. Harrison.eds. CURRENT Diagnosis & Treatment: Occupational & Environmental Medicine, 6e. McGraw Hill; 2021.