The side effects of taking vitamin B2 are mainly itching of the skin, numbness, tingling, burning and other abnormal sensations, as well as very yellow urination. Long-term oral intake of large amounts of vitamin B2 can lead to damage to kidney function, manifesting as elevated creatinine and urea nitrogen. At this time, we should stop the application of large amounts of vitamin B2, improve the examination and apply treatment to protect the kidneys if necessary. Vitamin B2 is stimulating to the kidneys because the excess vitamin B2 needs to be excreted through urine, which has a certain impact on the kidneys, especially the kidney units. In daily life, oral vitamin B2 is applied for some people with absolute deficiency, and it is best to apply it reasonably under the guidance of a doctor, otherwise side effects are likely to occur.