Maintaining a healthy-carb lifestyle often means reducing the amount of natural sugars (from sugar cane or sugar beets), in your diet. Sugar alcohols are commonly used in place of sugar in prepared foods. Some folks suffer gastric pain and upset, bloating, and diarrhea from them. If you suspect that you have an allergy to a sugar alcohol, the only way to know is to experiment until you isolate which one you need to avoid (or indulge in moderation).
Even if you don't have an allergy to sugar alcohols, they are heavy on carbs, so exercise moderation when you see one listed on a food label. Here are some names to be familiar with:
Erythritol
HSH (hydrogenated starch hydrolysates)
Isomalt
Maltitol and maltitol syrup
Mannitol
Sorbitol
Xylitol