Universal Blood Donor and Universal Recipient
Two blood types are special in transfusion: O negative can give red cells to everyone, and AB positive can receive red cells from everyone.
No A, B, or Rh antigens → safe for any recipient's red cells.
No anti-A, anti-B, or anti-Rh antibodies → can receive from anyone.
Why O Negative Is the Universal Donor
A transfusion reaction happens when the recipient's antibodies attack antigens on the donor's red cells. O negative red cells carry none of the A, B, or Rh D antigens, so there is nothing for any recipient's antibodies to attack. That is why O- is used in emergencies when there is no time to type the patient.
Why AB Positive Is the Universal Recipient
AB positive plasma carries no anti-A, anti-B, or anti-Rh antibodies. With no antibodies to react against incoming antigens, an AB+ patient can safely receive red cells from any of the 8 types.
The Plasma Twist
For plasma, the rule flips. Plasma compatibility depends on antibodies, not antigens, so AB is the universal plasma donor and O is the universal plasma recipient, the exact opposite of red cells. See the full compatibility chart for red cell pairings.
Why It Matters for Blood Supply
Because O negative works for everyone, hospitals rely on it for trauma and newborns, yet only about 7% of people are O-. That constant demand is why O- donors are always in short supply. Curious how common each type is? See rarest and most common blood types.