Vitamin C can be taken for a long time, but the amount you take each time should be controlled and not too much. When vitamin C is mildly deficient, you will have bleeding gums and puffy teeth in the morning when you brush your teeth, as well as poor daily mental state with depression and decreased immunity, and in severe cases, you will suffer from scurvy and subcutaneous bleeding. Vitamin C will be converted into oxalic acid in the body, which will generate oxalate in the urinary system, and oxalate will accumulate in the kidney to form kidney stones, urethral stones and other urinary stones. Because vitamin C generates oxalic acid in the body, oxalic acid is an acid that damages female reproductive cells and is detrimental to female pregnancy. Vitamin C can also damage osteoblasts, which are the key cells for children’s growth and development. However, long-term moderate consumption of vitamin C can avoid allergic reactions and scurvy, but also can strengthen the intestinal peristalsis to promote digestion.