O Negative (O-)

O negative (O-) is the universal red cell donor: its red cells can be given to any patient, whatever their blood type. It is relatively uncommon and in constant demand for emergencies and trauma.

Key traits

• Universal donor of red cells
• No A, B or Rh antigens on red cells
• Used for emergency transfusions when there is no time to test the patient's type
• Can only receive O- blood

Donating this type

• Hospitals try to keep a strategic stock of O- for emergencies
• Because it is uncommon, each O- donation is especially valuable
• Premature newborns often receive O- blood for safety

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.