What to and what not to mix with alcohol Are there any restrictions to mix alcohol with other things? A friend of mine mixed whisky with milk and then he turned sick. he got rashes all over his face. But when i searched a little bit it turned out it's fine to mix whisky and milk. I want to know are there any limitations for mixing or can we just add anything we want to alcohols(mostly any) for better taste.
The main hazards of mixing alcohol with milk are that you may denature the milk proteins and get curds.  Unpleasant, but probably not likely to provoke an allergic reaction.

Does your friend have any nut or pollen/tree allergies?  Depending on what the whiskey was casked in, there could be some residual allergens that were the actual culprit.