(1) Diarrhea is the most important symptom, which usually occurs 4 ~ 10 days after antibiotic application, or 1 ~ 2 weeks after drug withdrawal, or 5 ~ 20 days after operation. The degree and frequency of diarrhea are different. Lightly defecate 2 ~ 3 times a day, and you can heal yourself after stopping antibiotics. In severe cases, there is a lot of diarrhea, and the stool can reach more than 30 times a day. Sometimes diarrhea can last for 4 ~ 5 weeks, and a few cases can discharge patchy pseudomembranes, and bloody stools are rare.

(2) Abdominal pain is the most common symptom. Sometimes it is very intense, which may be accompanied by abdominal distension, nausea and vomiting, so that it is misdiagnosed as acute abdomen and surgical anastomotic leakage.

(3) The manifestations of toxemia include tachycardia, fever, delirium and disorientation. In severe cases, hypotension, shock, severe dehydration, electrolyte imbalance, metabolic acidosis, oliguria and even acute renal insufficiency often occur.