It will take approximately one and a half hour for each consumed drink to leave your body.
Again this is obviously an approximate answer as different drinks might take up different time too. Also it depends upon the persons immune system too.
For example, If you drink a large (250ml) glass of wine, your body takes about 3 hours to break down the alcohol. If you drink 1 pint of beer, your body takes about 2 hours to break it down.
The person is exhibiting signs of an allergic reaction. Asking questions such as "how long has this been happening" simply extends the time the person is suffering. However, asking if they have an epi pen can solve the issue immediately.
