Left-sided colitis needs to be treated according to the cause of the disease, such as ulcerative colitis, usually take aminosalicylic acid and glucocorticoid drugs for treatment, the specific way of medication and dosage, depending on the patient’s own situation. 1. Amino salicylic acid: this kind of drug is the first choice of drugs for the treatment of colitis, common drugs have LiuZhouSulphadiazine, mesalazine, etc., can play the role of analgesic, anti-inflammatory. 2. Glucocorticoids: common drugs are prednisolone. In the early stage of inflammation, glucocorticosteroids inhibit capillary dilation, reduce exudation and edema, and inhibit leukocyte infiltration and phagocytosis, thus reducing inflammatory symptoms. 3. Symptomatic treatment: timely correction of water and electrolyte balance disorders; severe anemia can be transfused, and those with hypoproteinemia should be supplemented with clear protein. Serious illness should be fasting, and give complete extra-gastrointestinal nutrition therapy. Severe diarrhea application of antidiarrheal agents (loperamide) can reduce intestinal peristalsis, but in severe colitis, antidiarrheal agents and antispasmodics need to be disabled, there is the possibility of inducing toxic megacolon. May also be other causes such as infection, ischemia, radiation enteritis, etc. caused by the left half of the colitis, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor to determine the cause and targeted treatment, do not take medication, so as not to delay the condition.