Ferrous sulfate blood supplementation is usually effective in about two weeks. 1. Whether or not ferrous sulfate supplementation is effective is generally determined by whether or not hemoglobin rises significantly. Oral ferrous sulfate blood supplementation due to different physical and absorption degree, the time of effect is not the same, absorption may be good in a week or so hemoglobin began to rise, in two weeks or so hemoglobin may rise significantly. 2. Although the effect can be seen in about two weeks, the course of taking ferrous sulfate usually takes about two months. This is because the body has a storage capacity for iron, which is stored after continuing to take the medication, and can be replenished from the storage in the event of insufficient iron intake by the body. Ferrous sulfate blood supplementation should follow the doctor’s instructions, and the doctor will determine the time of effect based on the auxiliary examination.