Which blood type is considered the universal donor?

Type O blood is considered the universal donor because it lacks A and B antigens on the surface of its red blood cells. This absence allows individuals with Type O blood to donate to any other blood type without the risk of an immune reaction. When a person with a different blood type receives Type O blood, their immune system does not recognize it as foreign, reducing the chances of transfusion reactions.

In transfusion practices, it is crucial to consider blood types due to the presence of antibodies in the plasma. For example, Type A individuals have anti-B antibodies, and Type B individuals have anti-A antibodies, which could lead to severe reactions if they receive incompatible blood. In contrast, Type O blood does not trigger these reactions since it contains no A or B antigens, making it safe for transfusions to patients of any other blood type.

This unique characteristic of Type O blood makes it the most sought-after type in emergency situations where the recipient's blood type may not be immediately known.