Here are some signs you should call your doctor if you are experiencing prolonged diarrhea: 1. You’re experiencing signs of dehydration: Diarrhea can cause dehydration because you’re losing so much liquid. In severe cases, dehydration can be life-threatening if it’s not treated. However, even if you don’t pass that threshold, being dehydrated feels awful and can easily be treated. 2. You have severe stomach or rectal pain: Severe stomach pain with diarrhea can signal many issues, from something as simple as gas to a potentially life-threatening condition like appendicitis. 3. There’s pus in your diarrhea: Pus is a liquid your body produces when trying to fight infection. 4. You have a fever of more than 102 degrees Fahrenheit: This generally indicates that you have some kind of infection that’s compromising your system. 5. You’re losing a lot of weight: If your diarrhea won’t stop and you lose a few pounds (on top of your normal fluctuations) in a few days, it could be a sign that you’re dealing with an issue like inflammatory bowel disease, a severe infection, or celiac disease.