After donating 400ml of blood, the recovery time varies for different blood cell components and plasma components, with a full recovery time of about 3 months. Blood donation of 400ml is basically equivalent to 1/10th of the total blood volume of an adult. blood consists of different components, including red blood cells, white blood cells and platelets, water, and plasma proteins. Usually, the blood volume can be restored to normal within 48 hours after donation, but the recovery of blood cells takes a long time, with white blood cells taking 5-7 days to return to normal; platelets taking 7-10 days to return to normal; proteins in the blood, such as albumin and various antibodies, often taking about a week to return to their pre-donation levels; and red blood cells are slower to recover, as the average life span of red blood cells is 120 days, and full recovery may take about 3 months. It may take about 3 months to fully recover. In addition, after donating 400ml of blood, patients need to take rest, drink more water, and enhance nutrition, such as protein supplementation, including milk and eggs.