The swelling of the lower body may be a physiological phenomenon, or it may be due to trauma, or infectious factors, skin allergies and other reasons. 1. Physiological phenomenon: in the state of sexual excitement, or just after sex, will cause the lower body swelling feeling, is a normal physiological phenomenon. 2. Trauma: the lower body is subject to external physical stimulation, bumps, scratches, extrusion, etc. can also cause swelling of the lower body. 3. Infectious factors: the external genitalia by bacteria, viruses, mycoplasma and other pathogenic bacteria infection, or inflammation of the urethra, can also cause the symptoms of lower body distension. 4. Skin allergies: for example, contact dermatitis of the vulvar skin, drug rash, insect bite dermatitis, etc. can also cause symptoms of lower body distension. There may be other reasons for the swelling of the lower body, you need to go to the hospital in time to check, clarify the cause of the disease, and follow the doctor’s instructions for treatment.