ABSTRACT
BACKGROUND Considering the ongoing coronavirus disease 2019 (COVID-19) pandemic, sufficient information about common and serious adverse events is needed to rapidly distribute COVID-19 vaccines worldwide. We report a case of neuroleptic malignant syndrome (NMS) with adrenal insufficiency after initial vaccination with Pfizer/BioNTech BNT162b2. CASE REPORT A 48-year-old man presented to the Emergency Department with fever and an altered mental status 7 days after receiving the first dose of the BNT162b2 COVID-19 vaccine. The patient had a history of end-stage renal disease and epilepsy treated with valproate. He was diagnosed with NMS based on the clinical findings of hyperthermia, muscular rigidity, and an elevated creatine kinase level. Additionally, a reduction in the response of cortisol to adrenocorticotropic hormone (ACTH) stimulation was observed in the rapid ACTH stimulation test. The patient was treated with dantrolene, bromocriptine, and hydrocortisone, and he responded well to treatment. Dantrolene and bromocriptine were tapered off over 4 weeks. Hydrocortisone was also tapered, and the patient was discharged on oral hydrocortisone (30 mg). CONCLUSIONS The present case suggests a possible link between the BNT162b2 COVID-19 vaccine and NMS with adrenal insufficiency based on the temporal relationship between vaccine administration and disease onset, although the patient was taking valproate, a potential cause of NMS. Having a high level of suspicion is important because the diagnosis of NMS with adrenal insufficiency is often challenging due to non-specific clinical manifestations. However, this case does not negate the utility of vaccination because these complications are extremely rare and can be treated with early diagnosis and proper management.