The left side of the stomach is always sore and swollen may be physiological reasons, but also pathological reasons, such as reproductive system diseases, urinary system diseases and so on. 1. Physiological reasons: if the left abdomen is sore and swollen during ovulation, it may be related to the rupture of the follicle when the left ovary ovulates. The follicular fluid stimulates the peritoneum when the egg is discharged, which can produce a feeling of soreness and distension, usually without other discomfort. 2. Reproductive system diseases: such as left salpingitis, left adnexitis, left ectopic pregnancy. Due to localized irritation of the peritoneum caused by inflammation, the left abdomen can be sore and distended, accompanied by a feeling of lower abdominal distension, and in the case of ectopic pregnancy, it is often accompanied by abnormal bleeding, menstrual disorders and other symptoms. 3. Urological diseases: such as left ureteritis, left ureteral stones. Due to the stimulation of stones and inflammatory substances, the patient may also have obvious left abdominal soreness, accompanied by urinary urgency, urinary frequency, urinary pain and other abnormal manifestations. If there is a left side of the stomach is always sore, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, with the help of the doctor to clarify the cause, and targeted treatment or treatment.