What is the universal donor blood type?

The universal donor blood type is O negative. This designation comes from the fact that O negative blood lacks A and B antigens, which means it can be transfused to individuals of any blood type without the risk of causing an immune reaction. Since O negative blood cells do not have these antigens, the recipient's immune system is less likely to recognize them as foreign, reducing the risk of transfusion reactions typically associated with incompatible blood types.

In emergency situations, O negative blood is particularly valuable because it can be given to anyone, making it a critical resource in trauma and critical care scenarios where time is of the essence and the recipient's blood type may not be immediately known. This characteristic of O negative blood is why it is often called the "universal donor" and is especially important in blood banks and medical facilities that need to ensure that patients receive safe and effective transfusions.

Other blood types, such as O positive, AB negative, and A negative, do not have the same universal compatibility due to the presence of A or B antigens or the Rh factor, which can trigger immune responses in recipients with different blood types.