what is the universal blood donor

The universal blood donor is someone with O negative blood type. This is because O negative blood can be used in transfusions for any blood type, making it the safest option in emergency situations where a patients blood type is unknown. O negative blood has no antigens, which means it will not trigger an immune response, even if the recipient has a different blood type. This makes it a very popular resource on hospital shelves, and it is in high demand yet in short supply.