It is narrated about Hazrat Ata that he was asked about a man who had a disease in his liver and it was suggested as a treatment for him to cut his liver and drink its blood. So Hazrat Ata said: There is nothing wrong in this, it is a necessity. Ibn Jurayj says: I asked Hazrat Ata, "Is blood not forbidden?" He replied: This drinking is due to necessity.

It is narrated from Hazrat Abu Ja'far, who says that when a person is compelled to use something, then that thing which is forbidden for a person becomes permissible.