What Blood Type Can You Not Donate to? Understanding Compatibility

September 30, 2025 •

5 min read

According to Abbott Newsroom, Type O- blood is the universal red blood cell donor, meaning it can be given to anyone in an emergency, but many donors are still unsure what blood type can you not donate to. Understanding your blood type's antigens and how they affect compatibility is key to ensuring safe and effective transfusions for recipients.

Quick Summary

Donation rules are determined by the ABO system and Rh factor. A recipient's immune system will reject foreign antigens in incompatible blood, highlighting the need for proper matching.

Key Points

Antigen Matching is Key: Blood type compatibility depends on the presence or absence of A, B, and Rh antigens on red blood cells.
Rh Factor Matters: A person with Rh-negative blood cannot receive Rh-positive blood due to potential immune reactions.
O-Negative is Universal Donor: Because it lacks A, B, and Rh antigens, O-negative red blood cells can be transfused to any blood type in an emergency.
AB-Positive is Universal Recipient: Having all antigens, an AB-positive person's body won't react negatively to blood from any other type.
Plasma Donors: While O- is the universal red cell donor, AB-negative individuals are universal plasma donors, since their plasma lacks anti-A and anti-B antibodies.
O Types Can't Receive A or B: People with O blood types can only receive O blood because their plasma contains both anti-A and anti-B antibodies, which would attack A or B cells.
Incompatible Transfusions Are Dangerous: A mismatch in blood type can cause a severe immune reaction, leading to complications like clumping and kidney damage.

The Core of Blood Compatibility: Antigens and Antibodies

Blood type compatibility isn't based on arbitrary rules; it's a matter of biology. On the surface of your red blood cells are inherited protein molecules known as antigens. Your specific combination of A and B antigens determines your blood group (A, B, AB, or O). A person with type A blood has A antigens, type B has B antigens, type AB has both, and type O has neither.

Additionally, your plasma contains antibodies, which act as defenders against foreign antigens. For example, a person with type A blood has anti-B antibodies in their plasma. If they receive type B blood, their anti-B antibodies will attack the donor's B antigens, triggering a serious immune response.

The Importance of the Rh Factor

Another critical component is the Rh factor, a separate protein antigen. Its presence or absence determines if your blood type is positive ($Rh+$) or negative ($Rh-$).

$Rh+$ blood: Contains the Rh antigen. People with $Rh+$ blood can receive either $Rh+$ or $Rh-$ blood.
$Rh-$ blood: Lacks the Rh antigen. People with $Rh-$ blood cannot receive $Rh+$ blood because they will produce antibodies against the Rh antigen.

What Happens During an Incompatible Transfusion?

Receiving incompatible blood can cause a severe and potentially fatal reaction, known as a hemolytic transfusion reaction. When the recipient's antibodies bind to the donor's red blood cells, it causes them to clump together. This clumping can block blood vessels and lead to serious complications, including kidney damage and organ failure. The strict blood matching process before any transfusion is what prevents this critical risk.

Specific Donation Rules: What Blood Type Can You Not Donate to?

Beyond the basic ABO and Rh guidelines, each specific blood type has its own set of donation restrictions. Your donor card holds the key to who you can help and who your blood is not compatible with.

O-Negative: The Universal Red Cell Donor

Despite being able to donate red blood cells to anyone, O-negative donors can not donate to recipients of any blood type if they are donating plasma, and they can not donate to themselves if they need a transfusion that's not also O-negative. While the red blood cells are safe for all, the donor's plasma contains both anti-A and anti-B antibodies. Therefore, O-negative individuals can only receive O-negative red blood cells. If an O-negative recipient gets any other blood type, their immune system will attack it.

AB-Positive: The Universal Recipient

AB-positive individuals possess both A and B antigens and the Rh factor, meaning their plasma contains no antibodies against A, B, or Rh proteins. This unique profile allows them to receive red blood cells from any other blood type. However, as donors, AB-positive individuals can not donate to any blood type other than AB-positive.

A and B Type Restrictions

A-Positive: Can not donate to any B blood type (B+, B-). It also can not donate to O blood types (O+, O-). Due to the Rh factor, it can not donate to any Rh-negative recipient (A-, B-, AB-, O-).
A-Negative: Can not donate to any B or O blood types. It can not donate to any Rh-negative recipients other than A- or O-.
B-Positive: Can not donate to any A blood type (A+, A-). It also can not donate to O blood types (O+, O-). Due to the Rh factor, it can not donate to any Rh-negative recipients (A-, B-, AB-, O-).
B-Negative: Can not donate to any A or O blood types. It can not donate to any Rh-negative recipients other than B- or O-.

Donation Compatibility Table

To simplify the rules for who you can and cannot donate to, consult the following table. It's important to know that while red cell donation is the most common form, plasma donations follow a different compatibility chart.


Your Blood Type	Can Donate Red Blood Cells To:	Cannot Donate Red Blood Cells To:
O-Negative (O-)	All Blood Types (Universal Donor)	Self as Plasma Donor, and no other Plasma Recipient than O- or AB-
O-Positive (O+)	O+, A+, B+, AB+	All Rh-Negative types (A-, B-, AB-, O-) and O-
A-Negative (A-)	A-, A+, AB-, AB+	O, B and any Rh-Negative that's not A- or O-
A-Positive (A+)	A+, AB+	O, B and any Rh-Negative types (A-, B-, AB-, O-)
B-Negative (B-)	B-, B+, AB-, AB+	O, A and any Rh-Negative that's not B- or O-
B-Positive (B+)	B+, AB+	O, A and any Rh-Negative types (A-, B-, AB-, O-)
AB-Negative (AB-)	AB-, AB+	All A, B, and O types
AB-Positive (AB+)	AB+ only	All A, B, and O types, plus AB-

Conclusion: Maximizing Your Lifesaving Potential

Knowing your blood type and its compatibility rules is one of the most proactive steps you can take to contribute to public health. While you cannot donate to every blood type, every donation is valuable. The most-needed types are always in flux, and organizations like the American Red Cross rely on a diverse pool of donors to meet hospital needs. Whether you are a universal red cell donor or have a more restrictive type, your gift of blood can make a profound, lifesaving difference when matched with the right recipient. By understanding the science behind blood compatibility, you can be an informed and confident donor every time you give.

The Role of Blood Donation

While compatibility is important, the need for blood remains constant. Traumas, surgeries, and treatments for chronic conditions like sickle cell anemia and cancer all require steady blood supplies. Every donation, regardless of type, helps maintain this crucial lifeline. To learn more or schedule a donation, visit the American Red Cross or a similar local blood bank.

A Quick Refresher on Donation Do's and Don'ts

Do: Find out your blood type if you don't know it. It's often tested during your first donation and can be provided to you by the donation center.
Do: Consider different types of donation, such as platelets or plasma, as compatibility rules differ and these components are also in high demand.
Don't: Assume your blood is not needed because it's not O-negative. Every blood type plays a vital role.
Don't: Guess your blood type or a recipient's. The lab must perform official testing before a transfusion.
Do: Spread awareness about the importance of blood donation within your community. Every type of donor is needed.

Frequently Asked Questions

As the universal donor for red blood cells, O-negative can donate to all major blood types, including A, B, AB, and O, regardless of Rh factor. However, they can only donate plasma to other O types or AB types due to the presence of anti-A and anti-B antibodies in their plasma. For red cell donation purposes, they have no restrictions.

A-positive individuals cannot donate red blood cells to B-positive, B-negative, or O blood types. Additionally, they cannot donate to any Rh-negative recipient (A-, B-, AB-, O-) because their red blood cells contain the Rh factor.

B-positive donors cannot give red blood cells to A-positive, A-negative, or O blood types. Similar to A-positive, they cannot donate to any Rh-negative recipient (A-, B-, AB-, O-) because of their Rh factor.

AB-positive is the most restrictive blood type for red blood cell donation, as these individuals can only donate to other AB-positive people. However, they are universal plasma donors, meaning their plasma can be given to anyone.

A person with Rh-negative blood must receive only Rh-negative blood for red cell transfusions. Receiving Rh-positive blood could trigger an immune response against the Rh antigen.

Matching blood types prevents a potentially fatal immune reaction. If incompatible blood is transfused, the recipient's antibodies will attack the donor's red blood cells, causing clumping, blocked blood vessels, and severe organ damage.

No, strict lab testing is always performed before a transfusion to ensure compatibility and patient safety. In emergency situations where the recipient's blood type is unknown, O-negative blood is used because it is the universal donor for red blood cells.