Progressively intensifying diarrhea, leading to dehydration. Appendicitis causes an intense infection of the intestines that causes their function to fail progressively. In the initial stages, you will experience this as constipation, but after that, diarrhea will begin and will become progressively more intense until the body is losing unacceptable levels of liquid. If the appendicitis itself is not treated, this will lead to inevitable dehydration and death.