If a patient has frequent swelling and pain in the legs, there are several reasons: 1. The most common factor is infectious. If the legs are infected by bacteria, viruses, fungi, or atypical pathogens such as mycoplasma and chlamydia, there will be extensive subcutaneous cellulitis, and there will also be dermatitis, and then the clinical symptoms of swelling and pain in the legs will appear. 2. When peripheral neuritis occurs in the legs, especially in patients with a past history of diabetes, it is particularly easy to develop peripheral neuritis in the legs, which leads to swelling and pain in the legs. 3. For example, patients with lumbar spondylosis, cervical spondylosis, sacroiliac arthritis and sciatic neuropathy will also have clinical symptoms such as frequent swelling and pain in the legs, accompanied by numbness and coldness, pain and discomfort.