When blood exits the body, it is impure and unclean, with the primary demand being that its transfer into another body is prohibited. However, in cases of necessity and extreme need, scholars have permitted the use of a woman’s milk by analogy, considering the impurity. Nevertheless, the ruling regarding its usage aligns with that of other impure and prohibited substances, meaning:

(1) When a patient is in a critical condition and there is no alternative to save their life according to a qualified doctor, it is permissible to donate blood.

(2) When there is a need for blood donation according to a qualified doctor, meaning the patient is not at risk of death, but there is a possibility of harm to their health if blood is not donated, then it is also permissible to donate blood.

(3) In situations where there is concern about the duration of the illness according to a qualified doctor, even in cases where blood donation is not necessary, it is permissible, but avoidance is better. In all these scenarios, donating blood is permissible, but receiving compensation for blood is not correct.

(4) When the sole purpose of blood donation is personal gain, adornment, or enhancing strength, in such a case, donating blood is not permissible