Hijama (cupping) breaks the fast according to the Madhhab. This ruling is restricted to cupping, and thus any other type of removal of blood, like donating blood, does not invalidate the fast.
This applies both to the one doing the Hijamah and the one getting it done.
This answer was collected from The Hanbali Madhhab website. The answers to the questions are given by Imam Zahed Fattah in accordance to the Hanbali School of Jurisprudence.