Gray stools may be dangerous. The normal color of stools is yellowish, while gray stools may be caused by the obstruction of bile excretion, resulting in the obstruction of bilirubin excretion, causing the decrease of urobilinogen and fecal bilinogen in the feces, and the lightening of the color of the feces. Generally speaking, if there is gray stool, it suggests that there is biliary obstruction, and the cause of obstruction may be gallstones, biliary tract tumors or pancreatic head cancer. However, if you have recently undergone barium meal imaging, grayish-white stools may also appear due to the effect of barium. Therefore, the appearance of gray stools need to pay attention to the timely visit to the hospital to clarify the cause of the disease and standardize the treatment.