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.
How to Blood Donations Work?
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.
How Can You Find Out Your Blood Type?
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 Are the Different Blood Types?
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 bloodtransfusion 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.
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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.
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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:
- 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.
What Are the Risks of a Blood Transfusion?
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.
Overview of Organ Transplants
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.
Red Cross Launches Initiative to Diversify Blood Donations
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.
Learn More:How the Immune System Works
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.(Video) Blood Donation Guide
What You Should Know Before Donating an Organ to a Loved One
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.
National Cancer Institute. ABO blood group system.
American Red Cross. Facts About Blood and Blood Types.
Dean L. Chapter 2, Blood group antigens are surface markers on the red blood cell membrane.In: Blood Groups and Red Cell Antigens [Internet]. Bethesda (MD): National Center for Biotechnology Information (US).
Dean L. Chapter 3, Blood transfusions and the immune system.In: Blood Groups and Red Cell Antigens [Internet]. Bethesda (MD): National Center for Biotechnology Information (US).
Red Cross. Facts about blood and blood types.
Delaney M, Wendel S, Bercovitz RS, et al. Transfusion reactions: Prevention, diagnosis, and treatment. Lancet. 2016;388(10061):2825-2836. doi:10.1016/S0140-6736(15)01313-6
Harewood J, Ramsey A, Master SR. Hemolytic transfusion reaction. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.
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Farhud DD, Zarif Yeganeh M. A brief history of human blood groups.Iran J Public Health. 2013;42(1):1-6.
American Red Cross. What Is a Universal Blood Type?.(Video) Blood Types Explained | Blood Groups (ABO) and Rh Factor Nursing Transfusions Compatibility
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Cleveland Clinic. Blood transfusion.
By Cherie Berkley, MS
Cherie Berkleyis an award-winning journalist and multimedia storyteller covering health features for Verywell.
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Is O+ is a universal donor? ›
O positive red blood cells are not universally compatible to all types, but they are compatible to any red blood cells that are positive (A+, B+, O+, AB+). Over 80% of the population has a positive blood type and can receive O positive blood.Why AB is called universal recipient? ›
Individuals with the AB blood group are known as universal recipients because they can receive blood from all blood kinds without experiencing any hemolytic reactions.Why O negative is the universal donor? ›
For emergency transfusions, blood group type O negative blood is the variety of blood that has the lowest risk of causing serious reactions for most people who receive it. Because of this, it's sometimes called the universal blood donor type.What blood type is the rarest? ›
What's the rarest blood type? AB negative is the rarest of the eight main blood types - just 1% of our donors have it.Is O Negative better than O positive? ›
Types O negative and O positive are in high demand. Only 7% of the population are O negative. However, the need for O negative blood is the highest because it is used most often during emergencies. The need for O+ is high because it is the most frequently occurring blood type (37% of the population).Can O positive receive blood from anyone? ›
What blood can O positive people receive? People with O positive blood can receive donations from: O positive blood donors. O negative blood donors.What blood can O Negative receive? ›
People with O negative blood can only receive red cell donations from O negative donors.How rare is a negative blood? ›
Is A negative blood rare? Around 8% of donors have A negative blood. In comparison, 30% of donors have A positive blood.What 2 blood types are not compatible for pregnancy? ›
A-B-O incompatibility occurs when:
- the mother is type O and the baby is B, A, or AB.
- the mother is type A and their baby is B or AB.
- the mother is type B and their baby is A or AB.
When a mother-to-be and father-to-be are not both positive or negative for Rh factor, it's called Rh incompatibility. For example: If a woman who is Rh negative and a man who is Rh positive conceive a baby, the fetus may have Rh-positive blood, inherited from the father.
Is blood type O Covid immune? ›
Our review shows that blood group O protects individuals against SARS-CoV-2, whereas blood group A predisposes them to being infected.What is the royal blood? ›
blood royal in American English
noun. all persons related by birth to a hereditary monarch, taken collectively; the royal kin.
The blood type of a child is determined by both of the parents. Each parent donates an allele for the ABO blood group. The A and B blood alleles are dominant while the O is recessive, meaning that the O will not be expressed when dominant genes are present.Can your blood type change? ›
CHANGES in blood type have been described in a variety of illnesses, usually acute infections or neoplasms.What is the best blood type to have? ›
Without any antigens or Rh D factor, O- blood is compatible with all other blood types. For that reason, people with O- blood are referred to as “universal donors.” According to the American Red Cross, every two seconds someone in this country needs a blood transfusion. That makes blood donations particularly critical.Why is O+ not a universal donor? ›
O positive blood can't be used universally because it has the Rh factor, but it is compatible with all positive blood types including O+, A+, B+, and AB+. Since over 80% of the population has a positive blood type, type O positive blood is in high demand.What is the disadvantage of O-negative? ›
Excessive use of O-negative leads to a shortage of blood supply compared to other types of blood. Individuals with O-negative blood generally have higher levels of stomach acid and are more likely to be exposed to medical conditions such as ulcers.What is the legendary blood type? ›
The rarest blood type is Rhnull. Unlike other blood types, people with Rhnull blood have no Rh antigens on their red blood cells. Researchers estimate that just 1 in 6 million people have Rhnull blood.Why is Rh-negative so rare? ›
For example, if someone's Rh factors are both positive, it is not possible for his or her child to have a negative blood type. Only people with at least one Rh-negative factors will have a negative blood type, which is why the occurrence of Rh-negative blood is less common than Rh-positive blood.Do full siblings have the same blood group? ›
Brothers and sisters don't always share the same blood type. The genotype of both parents plays a role in defining the blood type. For instance, children of parents with the genotypes AO and BO may have the blood types A, B, AB, or O. Thus, siblings do not necessarily have the same blood type.
How is O positive blood inherited? ›
Type B from one parent and type O or another type B gene from the other parent will give you type B blood. But inherit an A gene from one parent and a B from the other and you have AB type blood. Those with type O blood have inherited the O gene from each parent.What is the personality of O+ blood type? ›
Generally well-liked by most people; Very flexible, and adapt easily to change; They are easily influenced by others, as well as perceived authorities, such as television personalities; Generally trustworthy, but can sometimes make mistakes due to lapses of focus.Does O positive blood affect pregnancy? ›
Sometimes an incompatibility may happen when the mother is blood type O and the baby is either A or B. This can affect the newborn baby, who may need treatment after birth.What blood type Cannot take O negative? ›
This means that it's missing those things that could cause a bad reaction during a blood transfusion and can be given to any blood type. But this also means that people with O negative blood can only receive O negative blood.What two blood types make O negative? ›
What happened was that dad and mom each passed both an O and an Rh negative to the baby. The end result is an O negative child. Each of their kids has around a 1 in 8 chance of having O negative blood. This is possible because both O and Rh- are something called recessive traits.Is O negative the healthiest blood type? ›
Of the eight main blood types, people with type O have the lowest risk for heart disease. People with types AB and B are at the greatest risk, which could be a result of higher rates of inflammation for these blood types. A heart-healthy lifestyle is particularly important for people with types AB and B blood.What does your blood type say about you? ›
Currently, no scientific evidence supports a cause-and-effect relationship between a person's blood type and personality traits. Even using current investigative methods, a 2021 study examining blood type and personality demonstrated no significant correlation.Can a child have a different blood type than both parents? ›
Blood Type Compatability Predictor FAQs
Yes, a child is able to have a different blood type than both parents. Which parent decides the blood type of the child? The child's blood type is decided by both parents' blood type. Parents all pass along one of their 2 alleles to make up their child's blood type.
People with blood type A may be clever, passionate, sensitive, and cooperative. They can be loyal and patient, and they love peace. Sometimes, they may be overly sensitive about different things as compared with other blood types.
No it doesn't. Neither of your parents has to have the same blood type as you. For example if one of your parents was AB+ and the other was O+, they could only have A and B kids. In other words, most likely none of their kids would share either parent's blood type.
What blood type causes miscarriages? ›
Rh factor: Miscarriage can be caused because of the incompatibility of the mother's blood and the blood of the unborn foetus commonly known as Rh factor incompatibility. This type of miscarriage occur when the blood type of mother is Rh negative, and the foetus blood type is Rh positive.What blood type is hard to have babies? ›
Scientists from Yale University and the Albert Einstein College of Medicine have produced a study that finds patients with type O blood were at double the risk of diminished ovarian (egg) reserve than women of other blood types.Which two blood groups Cannot marry? ›
- If you have type A blood, you should only receive types A or O blood.
- If you have type B blood, you should only receive types B or O blood.
- If you have type AB blood, you can receive types A, B, AB, or O blood.
- If you have type O blood, you should only receive type O blood.
Theoretically yes, but it would be extremely rare. Two O parents will get an O child nearly all of the time. But as with anything in biology, there are occasional exceptions to this rule. New mutations -- or changes in the DNA -- are theoretically one way these kinds of uncommon scenarios can happen.What is B+ blood personality? ›
Usually have a strong drive to be the best at whatever they set their mind to doing; however, they also tend to neglect other tasks for the sake of whatever they are focusing on; Have a hard time multi-tasking; Tend to be loners, and keep themselves isolated from others.What blood type protects against COVID? ›
Risk of intubation was decreased among A and increased among AB and B types, compared with type O, while risk of death was increased for type AB and decreased for types A and B. We estimated Rh-negative blood type to have a protective effect for all three outcomes.Which blood group is most resistant to diseases? ›
Carriers of blood group 0 (I) are generally more resistant to diseases, with the exception of H. pylori-associated gastrointestinal diseases. Carriers of «antigenic» blood groups A (II), B (III), AB (IV) are more susceptible to development of infectious, cardiovascular and cancer diseases.Does type O blood have a antibodies? ›
blood group O – has no antigens, but both anti-A and anti-B antibodies in the plasma.Why do royals say blue blood? ›
Royals became known as 'blue bloods' because of their noticeable veins. Pale white skin came to be associated with wealthy royal families, who could afford to spend their times inside their mansions and palaces.Was Queen Elizabeth royal blood? ›
Historians have determined that Queen Elizabeth II is descended from Henry VIII's sister, Queen Margaret of Scotland, the grandmother of Mary Queen of Scots.
Does Taylor Swift have royal blood? ›
Taylor has a royal blood of Princess because she is a direct descendant of Robert II of Scotland who ruled as the King of Scots during the mid 1300s. He is her 20th Great Grandfather from her father's side.Does a father and child always have the same blood type? ›
While a child could have the same blood type as one of his/her parents, it doesn't always happen that way. For example, parents with AB and O blood types can either have children with blood type A or blood type B. These two types are definitely different than parents' blood types!Can two positives make a negative baby? ›
So, is it possible for two people who are Rh-positive to produce a child that's Rh-negative? The answer is yes — but only if neither parent passes along Rhesus D. The simple Punnett square here demonstrates how this is possible.What is special about O positive blood? ›
O positive red blood cells are not universally compatible to all types, but they are compatible to any red blood cells that are positive (A+, B+, O+, AB+). Over 80% of the population has a positive blood type and can receive O positive blood. That's another reason it's in such high demand.Do certain blood types live longer? ›
Chances are higher you'll live longer if you have type O blood. Experts think your lowered risk of disease in your heart and blood vessels (cardiovascular disease) may be one reason for this.Does blood type affect aging? ›
You can slather on as much sunscreen and buy as many anti-aging creams as you want, but how well your skin ages over time might depend on factors beyond your control—like your blood type. In fact, new research notes that your blood type, of all things, may play a big role in your susceptibility to wrinkles.Does blood type affect age? ›
No association between ABO blood group and longevity was observed by Vasto and colleagues12 in a study on 38 centenarians and 59 healthy controls.Why is O+ the universal donor? ›
Type O blood is called the universal donor because: It has neither A nor B surface antigens on the red blood cells.Can O Negative give blood to anyone? ›
O negative donors are often called 'universal donors' because anyone can receive the red blood cells from their donations. Although about 8% of the population has O negative blood, it accounts for around 13% of hospital requests for red blood cells.Can Type O Negative donate to O positive? ›
40% of the population, or 1 in 2.5 people, has type O-positive blood. Type O-positive blood can be transfused to any positive blood type: A-positive, B-positive, AB-positive, and of course other O-positives. Patients with O-positive blood can receive blood transfusions from other O-positives or O-negative donors.
What blood type can O positive accept? ›
Preferred donation methods: double red blood cell, whole blood, and platelet. Types O, A, B and AB positive can receive O+ red cells, and O+ platelets can go to anyone (except childbearing aged females of types O-, A-, B- and AB). Type O+ can ONLY receive types O+ and O-, and only type O+ and O- can receive O+ plasma.Can an O and an O+ have a baby? ›
Theoretically yes, but it would be extremely rare. Two O parents will get an O child nearly all of the time. But as with anything in biology, there are occasional exceptions to this rule.Is O negative and Rh negative the same? ›
Blood is further classified as being either "Rh positive" (meaning it has Rh factor) or "Rh negative" (without Rh factor). So, there are eight possible blood types: O negative. This blood type doesn't have A or B markers, and it doesn't have Rh factor.How can I check my blood type without a test? ›
Without drawing blood
A person may be able to use a saliva sample to test for their blood type. Around 80% of people produce the relevant antigens in their saliva. According to 2018 research , if a person secretes these antigens in their saliva, a dried saliva sample can reliably indicate their blood type.
Diseases more common in people with type O were:
- familial Mediterranean fever.
- systemic lupus erythematosus.
- systemic sclerosis.
- Sjögren's syndrome.
O+ blood has no A or B antigens, and is thus “O” blood. The (+) means that the Rh antigen is present. O+ blood is very important as a (mostly) universal red blood cell type.What blood type is O not compatible with? ›
People with type O blood will react against type A, type B, or type AB blood. People with type AB blood will not react against type A, type B, type AB, or type O blood.What should O positive blood type avoid? ›
- kidney beans.
- caffeine and alcohol.