How do you tell if someone is truly having an allergic reaction to alcohol or whether they are simply drunk?

Well firstly alcohol intolerance is much more unpleasant. Often it is the grains that the alcohol is made of that people are allergic to rather than alcohol itself. For example beer, wine, and liquor each contain the allergen histamine, produced as a result of the fermentation process.

Beer and wine also contain sulfites, used as a preservative but which are known to affect people with asthma.

Find out more about the symptoms and treatment here.