I have not tried Coke, but drink Pepsi occassionally. I have found if I drink in moderation - i.e. not more than 2 cans per week. I am fine with no reactions. However I have had 1 can two days in a row and my body can't handle it. I'm sick then for days. I do believe it's a combination of a build up of the carmel coloring and what your specific tolerance can handle.