Can liquor be used as a medicine?
As a principle, all things which are forbidden by Islam to eat or drink should only be taken in case of extreme emergency when there is no other way out. The Qur’ān says:
He has forbidden you dead meat and blood and the flesh of swine and that on which other name has been invoked besides that of God. But if one is forced out of necessity without wilful disobedience nor transgressing due limits, then this is no sin. (2:173)
Consequently, liquor can only be taken as medicine if everything else fails to save a life.
An interesting point to note here is that there is not a single disease at the moment whose sole medicine is liquor. Consequently, the answer above has an academic value only, and for all practical purposes no such situation or need has hitherto arisen.