Is it permissible to drink alcohol for medicinal purposes if a knowledgeable herbalist advises it, and does the Almighty’s saying apply to it: "But whoever is forced by necessity, neither craving it nor transgressing, there is no sin upon him"?

Alcohol differs from other impure substances in that it is forbidden to use it as medicine, according to the Prophet's (peace be upon him) saying: "It is not a medicine, but rather a disease." What your father did is impermissible. The necessity mentioned in the verse: (But whoever is driven by necessity, neither craving it nor exceeding due limit, there is no sin upon him) applies specifically to hunger and thirst. Many scholars have excluded alcohol from this, so it is not permissible to drink it even if one is thirsty, because it increases thirst and does not alleviate it, and because Allah has forbidden it absolutely. Some scholars differentiated between drinking it for medicine and for the necessity of thirst, permitting it for thirst but not for medicine due to the uncertainty of cure. Drinking it for medicine is never permissible. Your father must repent and not return to this act.