Colitis is caused by various reasons, leading to inflammatory lesions in the colon. Depending on the cause, it can be divided into nonspecific inflammatory changes and specific inflammatory lesions. It can be caused by bacteria, fungi, or parasites, with typical symptoms such as diarrhea and abdominal pain. Severe anemia and intestinal dysfunction may occur. Due to repeated diarrhea, an imbalance of acid-base equilibrium can happen. Patients generally see a gastroenterologist and require long-term treatment, as well as dietary adjustments.