Universal Blood Type Donors and Recipients

Who can donate blood to anyone or receive blood of any type

AB positive (AB+) and O negative (O-) are considered universal blood types. People who are AB+ are universal recipients, meaning they can safely receive a blood transfusion using any other blood type. O- individuals are universal donors, meaning their blood can be given to people of any blood type.

Having a universal blood type can save a life—either yours or someone else's—in an emergency. Only about 7% of people are O-, and their blood bank donations are in high demand because this type is used most often for those in need of a transfusion.

This article explains how blood typing works. You will learn what it means to be a universal blood recipient or a universal blood donor. You will also find out why blood types need to be compatible, and what happens if they are not.

Blood Types

To understand how universal blood donors and universal blood recipients work, you need to know the meaning of two key terms: antigens and Rh factor.


Antigens are a substance that the body's immune system can respond to. Antigens are found on the surface of blood cells. When the immune system detects an antigen that it does not recognize, it will fight it. 

The antigens on blood cells determine how a recipient reacts to a blood transfusion. The presence or absence of antigens helps categorize the different blood types.

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

Here are a few key points about blood types and antigens:

  • If you have blood type A, you have an A antigen.
  • If you have blood type B, you have a B antigen.
  • If you have an AB blood type, you have both A and B antigens. Since a person has all of the antigens that are possible, this blood type is the rarest.
  • If you have type O blood, you have no antigens. O negative blood is considered the universal blood donor type because it is compatible with type A, AB, B, and O positive blood.

Why Do Blood Types Have to Match?

Matching blood types is essential for safe blood transfusions or organ transplants. If a person gets the wrong blood type, their immune system attacks the donated blood cells rather than accepting them. This response can lead to kidney failure and shock. In rare cases, getting donated blood that's the wrong match can be fatal.

Rhesus (Rh) Factor

Blood types are described as being positive or negative. This is based on the presence or absence of a protein called the rhesus (Rh) factor. It's often written as "+" (positive or present) or "-" (negative or absent) when noting a person's blood type.

Here's how the Rh factor affects blood donation:

  • Rh-negative blood can be given to Rh-negative patients
  • Rh-positive or Rh-negative blood can be given to Rh-positive patients 

Since both A and B antigens are present in a person with AB+ blood and it has a positive Rh factor, the recipient will not reject the blood. That means a person who is AB+ is the universal recipient, as they can get any type of blood.

What Is a Universal Blood Recipient?
Verywell / Emily Roberts 

Blood Transfusion Reactions

A person can have a reaction to a transfusion if they receive the wrong type of blood. An allergic reaction to a blood transfusion is also possible, regardless of a person's blood type.

A hemolytic transfusion reaction is when there is a mismatch between the donor and recipients' A, B, and O blood types. Antibodies in the recipient's blood attach to the donor's red blood cells and destroy them in the recipient's bloodstream, liver, and spleen.

The body's response can cause a person to have a yellow tint to their eyes and skin (jaundice). It also can cause uncontrolled clotting in the bloodstream, shock, and rarely death.

Acute vs. Delayed Reactions

Blood transfusion reactions are divided into two categories: acute and delayed.

  • Acute reactions happen within 24 hours of a transfusion
  • Delayed reactions come later, and may happen two weeks to 30 days after a transfusion

Hemolytic reactions are rare because hospital blood banks type and crossmatch each unit of blood to be given to a recipient.

Allergic Reactions to Blood

An allergic reaction to a blood transfusion is also called an acute non-hemolytic transfusion reaction.

This type of reaction is not caused by a blood type mismatch—it happens because the recipient's body identifies the donor blood as a foreign invader and destroys the cells.

The symptoms of an acute non-hemolytic transfusion reaction include:

  • Itching
  • Fever
  • Chills
  • Skin rash

The symptoms of an allergic reaction often go away in a day or two and can be treated by stopping the transfusion. A person can also be given an antihistamine (like Benadryl) to help with symptoms.

If a person has a severe reaction to a blood transfusion, they may need to have more careful screening for blood in the future to prevent a similar reaction during later transfusions.

Organ Donation

Receiving a blood transfusion is not the only time being a universal blood recipient or universal blood donor matters. It also makes a difference when an organ transplant is needed.

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

The organ allocation system is set up so that it's fair to people waiting for a donor organ. This way, people with AB blood don't receive more organs than people with other blood types.


Universal blood donors and universal blood recipients are unique.

A person with a universal donor blood type can give blood that any person can receive. A person with a universal recipient blood type can get any blood donation, which can be life-saving in an emergency.

If you have the universal donor blood type, you know that giving blood can help a lot of people. That said, donating blood if you can is valuable no matter what your blood type is.

Usually, there is enough donated blood to help anyone who needs it; however, there can also be blood product shortages. Ongoing blood donations keep the supply stocked to help all patients in need.

Frequently Asked Questions

  • Why is O negative considered the universal donor blood type?

    A person with O- blood is a universal donor because their blood cells do not have certain antigens. These are substances that can trigger an immune response to a transfusion in some people. This leads to rejection of the blood, which can be serious.

  • Why is type O blood so common?

    O blood is one of the oldest blood types. It's so common because the genes for type O blood have been passed down for a long time. According to the American Red Cross, about 43% of the population has type O blood (either positive or negative).

  • Can your blood type change?

    Your blood type is determined by your genes, which means it's not something that will change throughout your life. However, there have been rare cases of people's blood types changing temporarily when they have certain blood cancers. There have also been rare reports of a patient's blood type changing after they get a bone marrow or organ transplant.

  • What is a blood transfusion?

    A blood transfusion is a medical procedure to help someone who does not have enough blood or its components (e.g., plasma, platelets, and red blood cells). The recipient gets the donor blood through an intravenous line (IV) inserted into a vein.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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