Chronic colitis is an inflammatory disease of the intestines. The lesion is mainly in the rectal and sigmoidal mucosa and submucosal layer, but may also involve the whole colon. Most cases of chronic colitis result from acute enteritis which is not cured of and is apt to frequently recur, commonly seen in young adults. The main clinical manifestations include repeated attacks of abdominal pain, diarrhea and mucous stools or bloody stools. This disease is included in the categories of "xie xie"(diarrhea), "li ji" (dysentery) and "fu tong" (abdominal pain) in traditional Chinese medicine.

It is due to invasion of external pathogenic factors, improper diet, emotional disturbance and protracted illnesses causing weak constitution, which cause dysfunction of the spleen and stomach, the failure of the small intestine to receive food and the failure of the large intestine in transportation. In this case the pure and turbid substances mix together, running down to the intestines. The chief pathogenic factor is dampness and the pathogenesis is excessive dampness and the dysfunction of spleen with the involve- mment in the spleen, stomach and intestines and the kidney and liver as well.