Even if silymarin is a well-tolerated molecule, it is necessary to point out the few cases of scientific evidence in literature that demonstrate potentially harmful effects: in a phase I clinical trial, the use of 13 g per day of silybin in patients affected by prostate cancer was correlated to hyperbilirubinemia and alanine aminotransferase (ALT) increase. The gene discussed is GPT; the disease is prostate cancer.