It may not have sugar, but candies or gum with contain sorbitol can cause tummy trouble. Sorbitol is not digestible and can cause stomach discomfort or even diarrhea in some people, Dr. Supapas warns. Diarrhea means dehydration—a sickness no-no. Artificial sweeteners may also trigger headaches. If you’ve got a scratchy throat and need relief, opt for a honey-sweetened cough drop, minus the sorbitol.