Menstrual blood provides a good nutritional environment for bacteria, fungi and parasites. During menstruation, bacteria, fungi and parasites are more likely to grow, making it difficult to control vaginitis and other diseases, or even progress or relapse, which can cause itchy labia minora. If you use sanitary products for a long time during menstruation, the vulva will be impregnated with menstrual blood and cause itching of the labia minora, etc. If you are allergic to sanitary napkins, it may also cause itching of the labia minora.