Hyperthyroidism, referred to as hyperthyroidism, may cause diarrhea. Hyperthyroidism is a hypermetabolic syndrome caused by an increase in the synthesis and production of thyroid hormones. Patients may experience panic attacks, sweating, fear of heat, increased appetite, weight loss, increased bowel movements or diarrhea, and in women, menstrual disorders. Treatment for hyperthyroidism may include antithyroid drugs, radioactive iodine or surgery. In addition, diarrhea should also be alerted to digestive disorders, and it is recommended to further check the stool routine and colonoscopy to rule out intestinal diseases. In conclusion, hyperthyroidism combined with diarrhea suggests further consultation with endocrinologists and gastroenterologists, and active treatment of the disease as prescribed by the doctor.