When a drunken person drinks from a certain cup, is it permissible for me to drink from the same cup?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If you want to know the Sharee'ah ruling on whether it is permissible to use a cup from which a drunken person drank, this is permissible. That is because the utmost is that the cup has been rendered impure and in this case it has to be washed and then used, like other pure utensils.

But if you are asking about the Sharee'ah ruling on drinking the remnant after a drunken person, then here is the answer in detail:

-        If alcohol was apparent on his mouth when he was drinking, and the content of the cup was in a liquid form, such as milk or juice, it is turned impure as soon as the alcohol touches it. Khaleel a Maaliki scholar, said: "The abundant amount of food in a liquid form is rendered impure as soon as an impure substance touches it, even if it is little."

-        If the drink is water and it has been changed by alcohol, it is also impure. If it has not been changed, it is also impure according to the majority of scholars. The Maaliki scholars, however, are of the view that a little water is not turned impure when a small amount of impurity comes in contact with it without changing any of its properties (taste, color or smell).

-        If there was no trace of wine in his mouth at the time of drinking, then the remnant is pure and permissible to use.

Nevertheless, it is better for a Muslim to keep away from socializing and intermixing with dissolute persons and from drinking what they left behind.

Allaah Knows best.