Literature reports about mitragynine toxicity in humans are rare, even if in recent years clinical cases are increasing. Only two papers reported cases of hepatotoxicity following kratom consumption; the first one was published by Kapp et al. in 2011 involving a 25-year-old man, the second one was described by Dorman et al. in 2015, involving a 58 year old man.
Although in both cases the available data were significantly suggestive of kratom induced hepatotoxicity, the authors of both studies due to the lack of scientific data on the toxicity of kratom in humans, were cautious in confirming unequivocally this association; in the first case the physicians could not directly correlate the onset of acute liver disease with the intake of kratom, taking into account that the effects of the substances contained in M. speciosa extract (alkaloids, saponins, flavonoids, etc.) have not yet been fully investigated making the correlation between the state of the liver and the intake of these preparations very difficult, whereas in the second case report, the authors defined idiosyncratic the onset of liver complications but evaluated as ?convincing? its association with the intake of kratom. However, it still remains to be established if the onset of liver complications could be attributable to kratom alkaloids, extract-production byproducts, or other contaminants