The reason for yellow urine after taking vitamin B2 is the problem of excretion of vitamin B drugs. Yellow urine after taking vitamin B2 is a normal phenomenon. Vitamin B2 is a water-soluble vitamin, a type of riboflavin, which will be metabolized by the kidneys after taking vitamin B2, thus making the urine yellow. Since vitamin B2 is not completely absorbed, it appears yellow when excreting the remaining vitamin. You can drink more water and urinate frequently to lighten the residue. If the situation is not improved, you can go to the hospital for a routine urine examination to see if it contains urobilinogen, if not, consider the cause of the multivitamin, examination and diagnosis to better know the specific cause, in order to timely and symptomatic treatment, so as to avoid continued aggravation of the disease. Daily life should also pay more attention to life diet, eat less spicy and stimulating, cold food, eat more vegetables and fruits.