Donated blood is supposed to be used to save the lives of human beings, and hence there is nothing wrong with donating blood to a blood bank. This is surely a charitable act that entails a high reward, in sha’ Allah.
Sheikh Muhammad Al-Mukhtar Al-Shinqiti, Director of the Islamic Center of South Plains, Lubbock, Texas, states the following: “Donating blood is an act of charity. It might save the life of a person who is in desperate need of it. Referring to this, Allah, the Almighty says: “…and if any one saved a life, it would be as if he saved the life of all mankind.” (Al-Ma’dah: 32). That is why I do not find any reason that you should stop donating blood as a charitable act. I should stress here that the best place where one can donate blood is a blood bank or health care institutions that are able to take care of it, store it, and classify it in a professional way.”