Every time you take a swig of soda or sparkling water, you swallow carbonation, sending gas into your digestive system and exacerbating your IBS. You may feel bloated, have stomach cramps or experience flatulence as your body tries to get rid of the excess gas. Carbonation can also irritate your digestive tract, causing diarrhea. Stick to naturally sweetened or unsweetened non-carbonated beverages, instead.