The human body is capable of replacing the plasma from one pint of blood within 24 hours, while it takes four to six weeks for the body to completely replace the red blood cells from one pint of blood, according to the American Red Cross. For this reason, eight weeks is required between donations of blood to ensure the health and safety of the donor.
After donating blood, the American Red Cross recommends drinking an additional 32 ounces of non-alcoholic fluids, refraining from any heavy lifting or exercising for five hours and eating healthy, iron-rich meals. A loss of strength or faintness may occur after giving blood. For this reason, it is important not to perform any activity that would put one's self or others in danger within several hours of donation. In the case of feeling dizzy or light-headed, lying down with the feet elevated until the feeling passes is recommended.
Donating blood is simple and helps to save lives. The entire process of blood donation takes just over an hour, with the actual blood draw lasting for just under 10 minutes. The remainder of the time is spent taking a medical history and mini-physical, then recovering after the blood draw is complete.