How often can I give blood?
Giving whole blood requires a waiting period of 56 days between donations (and is limited to no more than 6 whole blood donations/12 month period). If you donate plasma (your red cells are returned to you), you may donate every 28 days. If you donate platelets (your red cells and most of your plasma is returned to you), you may donate every 7 days, for a total of 24 times in the prior 12 months.
If you donate double red cells (most of your plasma is returned to you), you must wait 112 days before your next donation. Double red cell donors must meet certain weight, height and hemoglobin requirements.