Is it permissible for a person in Ihram to undergo bloodletting (cupping/Hijama)?
Chapter on What the Muhrim Must Avoid and What is Permissible for Him
Al-Mughni
Book of Hajj
Primary text
It is permissible to have blood drawn (cupping) without expiation according to the majority opinion, as it is a form of treatment akin to bloodletting or draining a wound. The evidence is the narration that the Prophet, peace be upon him, underwent cupping while in Ihram without any mention of expiation. Furthermore, it is not considered a luxury, thus paralleling taking medicine.
Supporting text
Imam Malik ruled that cupping is only allowed out of necessity. Hasan believed that the blood drawn should be regarded as a sacrifice (*damm*).