PT - JOURNAL ARTICLE AU - Felicity Norris AU - Patrick Mallia TI - Lesson of the month 2: A case of nitrous oxide-induced pancytopenia AID - 10.7861/clinmedicine.19-2-129 DP - 2019 Mar 01 TA - Clinical Medicine PG - 129--130 VI - 19 IP - 2 4099 - http://www.rcpjournals.org/content/19/2/129.short 4100 - http://www.rcpjournals.org/content/19/2/129.full SO - Clin Med2019 Mar 01; 19 AB - An 18-year-old female patient presented to the emergency department with non-specific neurological and gastrointestinal symptoms and was found to be pancytopenic. Her vitamin B12 level was low with a normal mean corpuscular volume and her full blood count 2 months previously had been within normal range. She reported heavy use of nitrous oxide over the previous 2 weeks and other investigations revealed no cause for her pancytopenia. Her pancytopenia resolved with discontinuation of nitrous oxide and vitamin B12 treatment. Heavy use of nitrous oxide should be considered as a cause of pancytopenia.