[Aerkuld]

What whisky do you have there?
It should be fine. High proof (distilled) alcohol has an infinite shelf life especially if unopened. If it is opened and has a sufficient amount of air in the bottle (half full say) then it can oxidize to some extent. It might make it taste a little different but it won't go bad to the point that there is anything wrong with it that would harm you.
As Shuie said, UV can affect it but it still wouldn't do you any harm to drink it. But if the bottles have been sitting in a cabinet that won't be a concern. He is also correct about it sitting in the bottle. If you bottle a 30 year old Scotch is will always be a bottle of 30 year old Scotch whether it was bottled yesterday or fifteen years ago.