Pulmonary embolus associated with a rare provoking factor: recreational nitrous oxide use

Pulmonary embolism (PE) is a common acute presentation which may be provoked by multiple factors. We present the unique case of a young man with no underlying health conditions who was diagnosed with bilateral PE which we believe was provoked by chronic use of nitrous oxide (NO), a potentially under-recognised risk factor for PE. NO is a substance that is commonly used recreationally, particularly among young adults in the UK. It has been shown to increase serum homocysteine levels which may create a prothrombotic state.Our patient had raised serum homocysteine levels on admission. He was anticoagulated and discharged with advice to stop nitrous oxide use. We recommend asking patients about recreational drug use when screening for provoking factors for PE so as to offer appropriate treatment and counselling.