INTRODUCTION: Wernicke's encephalopathy caused by thiamine deficiency is 
typically characterised by a mental-status change, oculomotor dysfunction and an 
ataxia. Pellagra is the clinical presentation of niacin deficiency comprising 
cutaneous, gastrointestinal and neuropsychiatric manifestations.
OBSERVATION: We report a case of encephalopathy due to dual vitamin deficiency 
of both thiamine (vitamin B1) and niacin (vitamin PP) in an 80-year-old women, 
hospitalized for severe sepsis caused by aspiration pneumonia. Severe 
malnutrition and alcohol consumption pointed to a diagnosis of vitamin 
deficiency. The clinical presentation and magnetic resonance imaging (MRI) were 
compatible with Wernicke's encephalopathy that remained irreversible despite 
vitamin B1 supplementation. Niacin supplementation allowed for complete 
regression of the observed symptoms compatible with niacin deficiency.
CONCLUSION: Malnourished and alcoholic patients showing signs of encephalopathy 
should receive supplemental multivitamins including niacin.