What Is the Universal Recipient Blood Type?

AB Positive Blood Is Compatible With All Other Types

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The universal recipient blood type is AB positive (also written as AB+), which means anyone with that blood type is able to safely receive a blood transfusion of any of the other blood types.

This matters because matching the correct blood type is critical to a successful blood transfusion or organ transplant as well a to the recipient's life. If a person receives incompatible blood during a transfusion or organ donation, the body treats it as foreign and the immune system attacks the donated blood cells rather than incorporate them into the body.

Such an attack can lead to serious problems, including kidney failure, shock, and a collapse of the circulatory system, In rare cases, receiving an incompatible blood donation can be fatal.

What Is a Universal Blood Recipient?
Verywell / Emily Roberts 

Blood Types

Antigens determine how a blood recipient reacts to a blood transfusion. An antigen is any substance the immune system can respond to. If the immune system encounters an antigen that is not found on the body's own cells, it will set off an attack to fight that antigen. 

There are seven blood types in addition to the universal recipient type. They are O positive, O negative, A positive, A negative, B positive, B negative, and AB negative:

  • O blood types are unique in that they have no antigens. O negative blood is considered the universal blood donor type because it is compatible with all A, AB, B, and O positive blood types.
  • If you have blood type A, you have an antigen that is specific and unique to A blood.
  • If you have blood type B, you have a B antigen.
  • The AB blood type means that both of the antigens for A and B blood are present. It is the rarest blood type. A person with AB blood has all of the antigens that are possible.

The universal donor blood type is O negative. Anyone with this blood type can donate blood to a person who needs it regardless of their blood type.

Blood types are characterized as positive or negative based on the presence or absence of a protein called Rh factor. Sometimes this apect of a blood type is expressed as a "+" (positive, or present) or "-" (negative, or absent).

Rh-negative blood is given to Rh-negative patients; Rh-positive or Rh-negative blood may be given to Rh-positive patients. Since both A and B antigens are present in a person with AB positive blood and it has a positive Rh factor, the recipient won't reject the blood.

Blood Transfusion Reactions

There is a difference between a reaction caused by transfusing the wrong type of blood—which rarely is fatal—and an allergic reaction to the blood transfusion, which is possible regardless of blood type.

A hemolytic transfusion reaction can occur when there is a mismatch between A, B, and O blood types of the donor and recipient. Antibodies in the recipient's blood attach to the donor red cells, and are then destroyed in the recipient's bloodstream, liver, and spleen. This can lead to jaundice and may cause uncontrolled clotting in the bloodstream, shock, and rarely death.

Hemolytic transfusions reactions are divided into two categories: acute and delayed hemolytic reactions. Acute reactions happen within 24 hours of a transfusion and delayed reactions occur after 24 hours. Delayed reactions may happen two weeks to 30 days after a transfusion. Since hospital blood banks type and crossmatch each unit of blood to be given to a recipient, these reactions are rare.

An allergic reaction to a blood transfusion is not caused by a blood type mismatch. It is caused by the recipient's body identifying the blood as a foreign invader.

The immune system then attempts to destroy the foreign cells. Also known as an acute non-hemolytic transfusion reaction, this type of reaction results in itching, fever, chills, itching, and a rash. It often passes in 24 hours to 48 hours and is treated by stopping the transfusion and administering a dose of a histamine-reducing medication such as Benadryl (diphenhydramine).

Unlike the reaction that happens when a person receives the wrong blood type, the reaction the body has to the blood that is identified as "foreign" can be treated effectively. 

A person who has a severe type of reaction to a blood transfusion may require more thoroughly screened blood in the future to prevent a similar reaction with subsequent transfusions.

Organ Donation

Receiving a blood transfusion is not the only time being a universal blood recipient matters. A person who needs an organ transplant could also potentially benefit from being a universal recipient.

A patient who needs an organ and has AB positive blood can accept an organ from donors of all blood types, just as they can accept blood of any type. However, the process of matching a donor and recipient is more complicated than only matching blood type.

The organ allocation system is also set up so that the distribution of organs is fair. That way, people with AB blood don't receive an unfair percentage of organs while recipients with other blood types receive fewer. 

A Word From Verywell

Individuals with AB positive blood are able to accept blood from donors of all blood types. While this is an interesting fact, there is typically an adequate blood supply for anyone with a need—regardless of their blood type—on any given day. 

Blood donations from a generous community make it possible for a patient of any blood type, rare or otherwise, to benefit from a transfusion of blood when needed.

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