The fastest recovery after blood donation is the blood volume, which usually returns to normal within 48 hours, but it takes longer for the blood cells to return to normal. It takes 5-7 days for white blood cells to return to normal, and 7-10 days for platelets to return to normal. The slowest recovery is for red blood cells, which take about 1 month to return to their pre-donation level. It takes about a month for the red blood cell count to return to its pre-donation level. It is important to take proper nutrition and eat more food rich in blood-forming materials. Therefore, after donating 400ml of blood, first of all, you should pay attention to rest, enhance nutrition appropriately and drink more water.