Pulmonary embolism associated with recreational nitrous oxide use: a case report

Recreational nitrous oxide (N 2 O) abuse has become increasingly prevalent, particularly among young adults. While neurological complications are well documented, thromboembolic events remain underrecognized. A 25-year-old man with a history of heavy recreational N 2 O consumption presented with retrosternal chest pain worsening with deep inspiration. Computed tomography pulmonary angiography revealed bilateral subsegmental pulmonary embolism with pulmonary infarction. Lower extremity venous duplex ultrasonography showed no deep venous thrombosis. The thrombophilia workup was unremarkable except for severe hyperhomocysteinemia (89 µmol/L; normal <12 µmol/L) associated with profound vitamin B12 deficiency (<150 pg/mL). The patient was treated with apixaban and vitamin B9/B12 supplementation. Follow-up biological assessment is pending due to suboptimal patient adherence. A report was filed with the regional addiction vigilance center. Recreational N 2 O use can lead to severe hyperhomocysteinemia through vitamin B12 inactivation, resulting in thromboembolic complications. Clinicians should consider N 2 O abuse in young patients presenting with unexplained venous thromboembolism and systematically screen for hyperhomocysteinemia and vitamin B12 deficiency in such cases.