Ruling on Blood donation or blood transfusion

Question 9: A man suffers anemia and the doctors in the hospital requested a blood transfusion for him. Knowing that blood is impure, is there any Rukhsah (concession) in Sharee`ah (Islaamic law) for a person who wants to donate blood for a patient who is in dire need of it? Is blood transfusion prohibited?

Answer: The basic ruling is that treatment must be with lawful things, which are permitted by the authority of Sharee`ah (Islaamic law)... read more here.