<p>Auto-brewery syndrome is a rare medical phenomenon caused by fungal gut dysbiosis in which ethanol is produced through endogenous fermentation by fungi or bacteria in the gastrointestinal system. The clinical manifestations of auto-brewery syndrome are related to the blood alcohol level concentration. A 16-year-old severely disabled cachectic boy with congenital brain malformations and cerebral palsy experienced substantial weight loss following COVID-19 infection 6 months before his death. He did not receive the COVID-19 vaccine. He was repeatedly treated for pneumonia, most recently a week before his death. He was found by his parents experiencing breathing difficulty and he could not be resuscitated. The autopsy revealed severe cachexia and gastric ulcers with fungal infiltration. The bacteria and Candida krusei detected through microbiological testing showed identical pattern as the fungi found in the stomach. Toxicological analysis using gas chromatography revealed a blood alcohol level of 0.75&#xa0;g/L. Death was attributed to pneumonia due to depletion of body reserves. A high peroral sugar intake in individuals with specific medical conditions (such as malnutrition, cachexia) may result in endogenous alcohol production when fermenting yeast or bacteria in the gastrointestinal tract becomes pathogenic, causing auto-brewery syndrome. Failure to perform microbial testing of the gastric and intestinal contents can result in incorrect interpretation of toxicological results. The incorrect interpretation of ethanol in the blood of a child (especially with severe disabilities) without considering auto-brewery syndrome can have serious medical, social and legal consequences. <i>Foetor ex ore</i> and signs of alcohol intoxication (such as poor coordination, slurred speech, impaired vision, etc.) with no history of alcohol consumption in disabled individuals with a history of high-sugar diet should prompt a clinician to suspect auto-brewery syndrome.</p>