Swollen tonsils with pain on one side are generally caused by two diseases: First, acute tonsillitis, which is caused by inflammation of the tonsils due to the invasion of bacteria and viruses after the decline of immunity and resistance. When the crypt opening on the tonsils is blocked, tonsillar secretions cannot be discharged out of the body, resulting in unilateral enlargement of the tonsils with pain, and examination reveals congestion and edema of the tonsils with pus moss or pus plugs visible on the surface. In terms of treatment, this acute inflammation requires symptomatic anti-inflammatory treatment and oral anti-inflammatory drugs, because most of what causes tonsillitis is hemolytic streptococcus, so infusion must be carried out, and cefotaxime sodium, ceftriaxone sodium, cefazolin sodium can be input, and it can gradually heal in about a week. Second, the symptoms associated with tonsillar tumors, generally seen as a cauliflower-like neoplasm on the surface of the tonsils, or crater-like ulcers, can cause unilateral enlargement. In the treatment, local pathology should be taken first, and after the pathology results are clear, surgery and radiotherapy and chemotherapy should be given.