Possible causes of sudden itching on both sides of the lips include: vulvar dystrophy, inflammation, ringworm, and vulvar eczema. 1. Vulvar dystrophy: lightening of the color of the vulvar skin and causing itching, and also atrophy of the vaginal opening due to the long duration of the disease. 2. Inflammation: Candida vaginitis, trichomonas vaginitis, mycoplasma and chlamydia infections can cause itching on both sides of the vulva. 3. Ringworm: Roughness and flushing of the skin on both sides of the vulva and inner thighs can be observed. 4. Vulvar eczema: it is an inflammatory skin disease, which will appear vulvar erythema with itching. There may be other reasons for the sudden itchiness on both sides of the vulva, and it is recommended to consult a doctor in time for symptomatic treatment. Avoid eating spicy and acidic foods, eat more fresh vegetables and fruits, stop smoking and drinking, and ensure a good night’s sleep.