O negative blood type
The universal red cell donor: O negative red cells can be given to anyone, which makes them the first blood used in emergencies.
6.6%
about 1 in 15 people · #4 of 8
What O negative means
O negative red cells carry no A, no B and no Rh D antigen, so no recipient’s ABO or Rh antibodies have anything to attack. That is why air ambulances and emergency rooms keep O negative on hand.
It is also the default for newborns and babies needing transfusion, and for Rh-negative women of childbearing age when their own type is unavailable.
The trade-off: O negative people can only receive O negative red cells. When supply is short they are among the most vulnerable patients.
Plasma
O- plasma can be given to O+, O-. A O- patient can receive plasma from O+, O-, A+, A-, B+, B-, AB+, AB-. Plasma rules run opposite to red cells because plasma carries antibodies, not antigens.
Best way to donate
Whole blood or double red cells. Only about 7% of Americans are O negative, yet O negative units are used whenever a patient’s type is unknown, so blood services ask these donors to give as often as they can.
Genetics
ABO genotype OO; Rh genotype dd. Want to know what blood type your children could have? Use the blood type calculator.
Pregnancy
An O negative mother carrying an Rh-positive baby can become sensitised. She is offered anti-D (RhoGAM) at around 28 weeks and after birth if the baby is Rh positive. Read the Rh factor guide.
O negative blood type FAQs
Who can O negative donate to?
All eight blood types can receive O negative red cells.
Who can O negative receive from?
Only O negative red cells.
Is O negative the rarest blood type?
No. About 6–7% of Americans are O negative. AB negative (under 1%) and B negative (under 2%) are rarer.