Long-term injection of estrogen may cause low hemoglobin. 1. First of all, long-term injection of estrogen will lead to a decrease in androgens in the body, androgens can promote the increase of erythropoietin, and a decrease in androgens leads to a decrease in erythropoietin and a decrease in hemoglobin, and red blood cells of males will fall to the level of females. 2. Secondly, estrogen will reduce the activity of glutamate hydroxypeptidase, which will inhibit the absorption of folic acid. At the same time, estrogen has an enzyme-promoting effect, which can increase the content of liver herbal enzymes and accelerate the metabolic rate of folic acid, which will lead to a decrease in hemoglobin and produce anemia. Prolonged injection of estrogen leads to a significant decrease in hemoglobin and severe anemia, it is recommended to go to the hospital in time.