Adult diarrhea and fever are considered to be caused by the following factors: a. Acute gastroenteritis. Acute gastroenteritis is an acute inflammatory lesion of the gastrointestinal mucosal tissue. Irregular diet, overeating, like to eat spicy and stimulating food, diet unhygienic, eat spoiled food, do not pay attention to keep warm abdomen cold, etc. can cause acute gastroenteritis, acute gastroenteritis main symptoms are nausea, vomiting, diarrhea, abdominal distension, abdominal pain, fever. Diarrhea and fever is a bacterial infection, need to take antibiotics for anti-infection treatment, such as haloperidol. During treatment, you need to drink more water to prevent dehydration caused by diarrhea. Ulcerative colitis. Ulcerative colitis is an ulcerative lesion of the colonic mucosal tissue, which can cause abdominal pain, diarrhea, fever and other symptoms, and can be treated with salicylate preparations of sulfasalazine or dexamethasone.