The 2,200-bed hospital sees demand of between 150 and 200 units of blood daily, but donations have fallen short of demand recently, leaving the hospital short.
The facility must maintain 4-5 days of supply and cannot only rely on the Red Cross National Blood Centre, which is expected to distribute several thousand units to hospitals nationwide every day, said Dr Parichart Permpikul, head of the Siriraj's transfusion medicine department.
The hospital blood bank faces most severe shortages in Group A and B due to high demand from patients, she added.
People in good health were urged to donate blood at Somdej Ya 90 Years Building every day (8.30am-6pm on weekdays and 8.30am-4pm on weekends), or call 0-2419-8081 ext. 123 and 128.