Volunteers donate all blood products used for transfusions performed in the United States to help people who are sick, injured, or who need blood for other reasons. Some volunteers undergo a procedure called apheresis, which removes only the red blood cells, plasma, platelets, or certain types of white blood cells. Some people donate stem cells through apheresis for family members or other people who need blood and bone marrow transplants. A person can also have their own blood drawn and keep it for a few weeks before surgery in case needed.

In most places, you must be in good health, be at least 16 years old, and weigh at least 110 pounds to donate blood. There is no weight limit. You cannot donate blood if you are pregnant or have certain conditions, such as HIV or sickle cell disease. If you have sickle cell trait, you may donate platelets, but you should not donate whole blood, as this will interfere with the later steps in handling the donated blood. You may need to wait before you can donate, including if you have anemia, are taking antibiotics, have a cold or the flu, or have received a blood transfusion in the past year.

Blood donations can take place at a blood bank, a special blood donation center, mobile facilities or a hospital. Sometimes blood donations take place during special events called blood drives. The time it takes to donate blood from start to finish depends on the type of blood donation; for example, it takes about 1 hour to complete a plasma or whole blood donation and about 2 to 3 hours for a platelet donation obtained by apheresis

All donated blood products are carefully tested and then stored or shipped so that they are ready for patients in need of a blood transfusion. You can donate whole blood as often as every 8 weeks. Or, certain donors may undergo red blood cell apheresis to donate two units of red blood cells every 16 weeks, which is twice as many as with whole blood donation. At the NIH Blood Bank, men can donate AB plasma and men and women can donate platelets every 4 weeks by apheresis.

Most healthy adults can donate blood without experiencing side effects. Some people experience dizziness or nausea after donating blood. To help prevent these complications, you may be asked to sit for 15 minutes after donating blood. You can also get something to eat or drink during this time. In addition, because donating whole blood or red blood cells removes iron from the body, these donors need to make sure they get enough iron from food or supplements.