NHS Blood and Transplant needs people with these blood types to donate now as demand increases.
The lack of O negative and B negative donors giving blood in the run up to the bank holiday has meant stocks of these groups could fall below two days.
O negative is the universal blood group and is often used when a patient’s blood type is not known. It is also being used as an emergency substitute for Ro blood.
This rare subtype is more common in black people and there is a huge shortage of Ro blood donors.
B negative stocks are also low because many patients with serious blood disorders, like sickle cell, need B negative blood. Only two per cent of donors have this blood group.
Mike Stredder, director of blood donation at NHS Blood and Transplant, said: ‘The overall demand for blood is declining year on year.
‘However, the need for specific blood groups such as Ro blood type and O negative are on the increase.
‘We need an additional 4,000 regular O negative donors to those we have now to consistently provide seriously ill patients with the blood they need.
‘If you know you are O negative or B negative and have never donated before, now is the time to make a difference.’
O negative and B negative donors can walk in and donate at most of the NHS Blood and Transplant fixed-site donor centres, without the need to make an appointment.
The nearest site is Southampton Blood Donor Centre, on Coxford Road.
Alternatively call 0300 123 23 23 to ask for a priority appointment at a community blood sessions.