The World Federation One Stop Fiqh

Ruling 336

If phlebotomy33 has been performed on one of the parts of the body on which wuḍūʾ is performed and water is not harmful for it but the person is unable to wash it because the blood does not congeal and suchlike, then it is necessary for him to perform tayammum. However, if one can wash it with water but water is harmful for it, then he must act according to the rules of jabīrah.

33 Phlebotomy is the practise of bloodletting, i.e. a treatment in which a vein is cut to release blood.