PT - JOURNAL ARTICLE AU - William Osborne AU - Aneeka Chavda AU - George Katritsis AU - Jon S Friedland TI - Lesson of the month 1: A rare adverse reaction between flucloxacillin and paracetamol AID - 10.7861/clinmedicine.19-2-127 DP - 2019 Mar 01 TA - Clinical Medicine PG - 127--128 VI - 19 IP - 2 4099 - http://www.rcpjournals.org/content/19/2/127.short 4100 - http://www.rcpjournals.org/content/19/2/127.full SO - Clin Med2019 Mar 01; 19 AB - Flucloxacillin, a beta-lactam antibiotic, is a commonly prescribed antibiotic for the treatment of infections caused by staphylococci and streptococci, most notably Staphylococcus aureus. Paracetamol is one of the most dispensed medications by NHS England and is used for the treatment of fever and pain.1 However most doctors are unaware that concurrent use of these drugs can cause a potentially fatal drug interaction due to pyroglutamic acidosis (PGA), also known as 5-oxoprolinaemia. PGA is a rare cause of raised anion gap metabolic acidosis due to disruption of the γ-glutamyl cycle. We report the case of a patient with multiple comorbidities who developed PGA due to coadministration of paracetamol and flucloxacillin.