Which blood type is the universal donor?
Quick Answer
O negative (O−) is the universal red blood cell donor — it can be given to patients of all ABO and Rh blood types. Only about 7% of the population has O− blood.
The Full Story
O negative (O−) blood is the universal donor for red blood cells because it lacks A, B, and Rh(D) antigens on its surface, meaning it won't trigger an immune reaction in any recipient. This makes it critical in emergencies when there's no time to determine a patient's blood type. Only about 7% of the population is O−, making it constantly in high demand. For plasma donation, the roles reverse: AB+ is the universal plasma donor. The ABO blood group system was discovered by Karl Landsteiner in 1901, earning him the Nobel Prize in 1930. Blood type distribution varies by ethnicity: O+ is the most common type globally (~37%), while AB− is the rarest (~0.6%). Your blood type is determined by genes inherited from your parents.
Key Facts
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Suggested video title for this topic:
"The Rarest Blood Types — And Why O Negative Saves the Most Lives"