The dangers of ingesting kombucha include illness from bacterial contamination and unexpected ingestion of alcohol resulting from fermentation, according to WebMD. Additional potential dangers are mycotoxicity from mold growth and lactic acidosis, Mother Jones explains. In addition, unproven health claims associated with kombucha can mislead consumers about its benefits and risks.
The danger of bacteria-caused illness primarily results from homemade kombucha, which is unpasteurized and may have been prepared in a nonsterile environment, WebMD notes. Consumers can mitigate the risk posed by bacterial contamination by purchasing a pasteurized commercial product.
Unrefrigerated, unpasteurized kombucha can continue to ferment after packaging, which can increase its alcohol content above the 0.5 percent legal limit, WebMD warns. In these cases, the kombucha can have as much alcohol as beer.
In 2009, a male patient's kombucha use may have caused lactic acidosis, which results when the bloodstream contains excessive levels of lactic acid, according to Mother Jones. The patient's illness was serious enough to require hospitalization.
Reports of kombucha's effectiveness in treating or preventing conditions such as sleeplessness, overweight, hair loss, sluggish liver function and cancer stem mostly from anecdotal evidence and animal studies and therefore remain unproven, WebMD cautions. Although the probiotic kombucha contains is thought to aid digestion and boost immunity, pasteurization eliminates the probiotic and thus its possible benefits while increasing the risk of illness from contaminated product.