Pain on the sides of the thighs can be caused by physiologic factors such as lactic acid buildup due to excessive exercise. It may also be caused by diseases such as synovitis of the hip joint and pudendal nerve entrapment. 1. Physiological factors: Usually due to over-exercise, the muscles on both sides of the thighs are stiff and lactic acid builds up, leading to pain on both sides of the thighs. This symptom will gradually disappear with time. 2. Hip synovitis: After the hip joint has synovitis, it will stimulate the surrounding blood vessels and cause vasoconstriction, which will easily lead to the slowing down of the local venous return, and after the decrease of venous return, the metabolites at the distal end of the hip joint will accumulate and increase, which will lead to the symptom of pain on both sides of the thighs. 3. Cortical nerve entrapment: it is usually due to the entrapment of the anterior lateral femoral cortical nerve at the iliac crest, which causes the symptoms of pain on both sides of the thigh. If the patient has the symptom of pain on both sides of the thigh, it may be caused by venous thrombosis, lumbar disc herniation and other diseases, and it is recommended that the patient should consult the doctor in time to clarify the cause of the disease, and standardize the treatment according to the doctor’s instructions.