Many women always like to buy some "nursing liquid" and "cleaning liquid" to clean vulva and vagina, which is euphemistically called "health care", but in the end they often have to go to the hospital because of severe vaginitis. Why is this? The pH value of normal female vagina is between 3.8 and 4.4, which is most suitable for the proliferation of lactobacillus in vagina. At the same time, vaginal mucosal cells will secrete more glycogen for the growth of Lactobacillus, and other pathogenic microorganisms will be inhibited, thus forming a virtuous circle chain. Therefore, the vaginal environment of normal women is "self-purification". However, after the pH value in vagina changes, it is very vulnerable to the invasion of external microorganisms or the reproduction of conditional pathogenic microorganisms in vagina, resulting in vaginitis. For example, if the vagina is washed with water, the pH value in the vagina will rise from about 4.0 to above 5.2, and Trichomonas vaginalis, which is suitable for growing in a humid environment with a pH value of 5.2~6.6, will grow and reproduce. If the vagina is washed repeatedly with washing liquid, a variety of antibiotics are used for a long time, or "pads" (especially those with drugs) are used for a long time, people wearing tight chemical fiber thick underwear and obese people are very suitable for the mass reproduction of candida (candida, mold), thus causing infection. According to the data released by relevant quality monitoring departments, the pH value of female nursing liquid produced at home and abroad is defined as 4.0~4.5. If the vulva and vagina are washed with a solution with pH value of 3.5 for a long time under the condition of normal vaginal pH value, the pH value of vagina will decrease and the acidity will increase, which is beneficial to the growth of yeast and the formation of fungal vaginitis. On the contrary, if the solution with pH value of 4.5 is used for a long time, the pH value of vagina will increase, and the acidity will decrease, thus inhibiting the growth of lactobacillus, which is beneficial to the growth of conditional pathogenic bacteria in vagina and may lead to bacterial vaginosis. Because the pH value of human skin (including vulva skin) is between 5.0 and 5.6, and the pH value of the mucosa inside the labia minora and around the urethral orifice is about 5.0, if the vulva is washed with a solution with a pH value of 3.5 to 4.5 for a long time, not only will the oil film and acid film on the skin and mucosa be washed away, but also the local skin and mucosa will lose their moisturizing and protective functions. Skin and mucous membrane with low pH caused by external lotion are easy to become sensitive and cause itching. When skin and mucous membrane itch occurs, wash with external lotion. Because some solutions contain mint, it makes people feel cool and comfortable for a short time after washing, prompting you to wash every day. If you don't wash it, you will feel uncomfortable, just like addiction. The more you wash, the more itchy you get. In clinical work, the author often meets some patients who blindly use external washing drugs. Even after stopping using lotion, some people will have intermittent itching and discomfort within two or three months, and they always want to get comfortable again with lotion. In fact, soaking or washing the vulva with drugs, the role of drugs can not enter the vagina, and it can not play a role in treating vaginitis at all. This is determined by the anatomy and physiological structure of vagina. Although the vaginal opening leads to the outside world, the front and rear walls of the vagina are closely attached. Don't say that soaking in liquid medicine can't penetrate into the vagina at all. Even if you are swimming and diving, you can't put water pressure into the vagina when the water pressure is very high. If water enters the vagina when swimming or diving, it will soon be filled with water. Which woman dares to swim? Therefore, for patients with vaginitis, washing medicine outside is also a white wash.