Which blood types are compatible with each other?
Compatibility depends on ABO type and Rh factor. O negative (O-) is the universal red cell donor. AB positive (AB+) is the universal recipient.
Blood type compatibility is determined by two systems: ABO (A, B, AB, O) and the Rh factor (positive or negative). Giving incompatible blood can cause a serious hemolytic reaction.
Who can receive from whom (red cells)
| Recipient type | Can receive from |
|---|---|
| A+ | A+, A-, O+, O- |
| A- | A-, O- |
| B+ | B+, B-, O+, O- |
| B- | B-, O- |
| AB+ | All types (universal recipient) |
| AB- | A-, B-, AB-, O- |
| O+ | O+, O- |
| O- | O- only |
Universal donor: O negative
O negative red cells have no A, B or Rh antigens, so they can be given to any patient. That is why hospitals rely on O- in emergencies and why it is always in demand.
Universal recipient: AB positive
People with AB+ can receive red cells from any type. As donors, they can only give red cells to other AB+ patients.
A note on plasma
Plasma works the other way around: AB plasma has no anti-A or anti-B antibodies, so it can be given to patients of any type, while AB patients can only receive plasma from AB donors.
Why mismatches are dangerous
The immune system attacks foreign antigens and destroys incompatible red cells. That can cause kidney failure, shock and death.
To learn your type, see our question on how to find out your blood type.
This information is general and does not replace advice from a health professional. Your eligibility is always decided at the donor screening on the day of donation. Rules change, so confirm with the American Red Cross or the blood center where you plan to donate.