O negative, written as O- is called the universal donor for red blood cells. O- red blood cells can generally be given to people with different ABO and Rh blood groups. This makes O- especially important during emergencies. Keep reading to know in detail.
Why Is O Negative Called the Universal Donor?
O- red blood cells do not have A antigens. O- red blood cells do not have B antigens. They also do not have the RhD antigen. The absence of these major antigens makes O- red blood cells compatible with different blood groups.
What Are the Main Blood Groups?
There are four main groups in the ABO blood group system:
| Blood Group | Antigens Present on Red Blood Cells | Rh Factor Variants |
| A | Has A antigen | Rh positive (+), Rh negative (-) |
| B | Has B antigen | Rh positive (+), Rh negative (-) |
| AB | Has both A and B antigens | Rh positive (+), Rh negative (-) |
| O | Does not have A or B antigens | Rh positive (+), Rh negative (-) |
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What Makes O Negative Different From O Positive?
Both O- and O+ red blood cells do not have A or B antigens. O- does not have the RhD antigen. O+ has the RhD antigen. Because O+ has the RhD antigen, it is not universally compatible with Rh-negative patients. O- is therefore the universal red blood cell donor.
Which Blood Group Is the Universal Recipient?
AB positive or AB+ is known as the universal recipient for red blood cells. AB+ red blood cells have A, B and RhD antigens. People with AB+ blood can generally receive red blood cells from all eight commonly recognised blood types. This is the opposite of the universal donor concept.
Which Blood Group Is the Universal Plasma Donor?
AB blood is known as the universal plasma donor. Plasma compatibility is different from red blood cell compatibility. AB plasma does not contain anti-A or anti-B antibodies. This allows AB plasma to be given to patients from different ABO blood groups in appropriate circumstances.
How Common Is O Negative Blood?
O- is a relatively uncommon blood type. The American Red Cross states that around 7% of the US population has O- blood. Despite being less common, O- blood is highly important for emergency transfusions.
O Negative Blood: Key Facts
| Parameter / Attribute | Details |
| Blood Group | O negative (O−) |
| Common Name | Universal red blood cell donor |
| A Antigen | Absent |
| B Antigen | Absent |
| RhD Antigen | Absent |
| Universal Red Blood Cell Recipient | AB+ |
| Universal Plasma Donor | AB |
| Main Importance | Emergency red blood cell transfusions |
| Commonly Recognised Blood Types | Eight, including O− |