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Can a person fast if he is getting a blood transfusion in hospital?
No. A person receiving a blood transfusion is advised not to fast, on medical
grounds. They may fast on the days when no transfusions are required.
Contemporary Muslim jurists unanimously agree that blood transfusion for medical purposes is permissible. A Muslim is allowed to receive and donate blood for medical reasons. In Muslim countries it is very common nowadays to find that religious scholars and Imams are asked to urge people to make blood donations to hospitals for public welfare. These matters are related to human life. Islam teaches us to feed the hungry, to take care of the sick and to save people's lives.
However, as
Sheikh Ibrahim Desai states, the permissibility of blood donation or blood transfusion is determined by the following conditions:
a) The donor should donate his blood willingly. If he is compelled to do so, then it is not permissible;
b) There is no danger to his (the donor's) life or health;
c) It must be clarified by the doctor that blood transfusion is necessary otherwise the life of the patient will be at stake; i.e. the recovery can not be possible without blood transfusion.
d) It is not permissible to sell one's blood or to pay the blood donor. However, if one is desperate for blood (to save his life) and the only means to obtain it is to purchase it, then it is permissible to pay for the blood. [In this case, it is only the one who asks for the money that will incur the sin].
source: islamonline.com?
Among the things that break the fast are things that are classified as being like eating or drinking, such as taking medicines and pills by mouth, or injections of nourishing substances, or blood transfusions.
Injections that are not given to replace food and drink but are used to administer medications such as penicillin and insulin, or tonics, or vaccinations, do not break the fast, regardless of whether they are intra-muscular or intravenous. (Fataawa Ibn Ibraaheem, 4/189).
source:
http://www.sultan.org/fasting.html#The%20sick