One who is advised to drink his own blood

It is reported about Ata that he was asked about a man who had an ailment in his liver, for whom the treatment prescribed was that he cut at his liver and drink its blood. Ata said: There is no harm in this; it is a necessity. Ibn Jurayj said: I said to Ata: Is blood not forbidden? He said: This drinking is because of necessity.

It is narrated from Abu Ja'far, who said: When a person is compelled to use a thing, then what was forbidden to him becomes lawful.