Health officials in England and Wales have launched an urgent appeal for blood from O negative and B negative donors, amid fears stocks will run dry in just two days.
NHS Blood and Transplant (NHSBT) has warned it is running dangerously low on supplies, blaming low donations over the bank holiday weekend as temperatures soared.
NHSBT are asking anyone who knows they have these blood types but may have not donated before to give blood now.
There is currently an urgent appeal for more people from the black community to give blood as well. NHS Blood and Transplant needs at least 40,000 new black donors to help patients.
Over 7,000 have come forward since an appeal last June, but more are needed to help ease the pressure on blood stocks and make sure people in need receive the best possible blood match.
The 'universal' blood group
O negative is also the '˜universal' blood group and is often used when a patient's blood type is not known, such as emergency situations.
B negative stocks are low because many patients with serious blood disorders, like sickle cell, need B negative blood. Only two percent of donors are B negative.
O negative and B negative donors can walk in and donate at most of the NHS' fixed site donor centres, without the need to make an appointment, or can call 0300 123 23 23 to ask for a priority appointment.
There is an urgent call for donors of some blood types across England. Shutterstock
Mike Stredder, director of blood donation at NHSBT, 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.'
For more information on how to give blood, call 0300 123 23 23 or visit www.blood.co.uk