Did Imam Shafi'i permit treating with alcohol?

The basic principle is the impermissibility of treating with unlawful or impure substances, due to the Prophet's (peace be upon him) prohibition of "foul medicine" and his saying concerning alcohol: "It is not a cure, but rather a disease." It is not permissible to treat with them except out of necessity and in the absence of a permissible and pure alternative, based on Allah's saying: "And He has already explained to you what He has forbidden to you, except for that to which you are compelled." This is the view of the Shafi'is and others. It is permissible to treat with impure substances when a pure alternative that can serve the same purpose is unavailable.