To prevent STDs, positive measures include regular sex partners, avoiding prostitutes, not having sex with unknown persons or persons with obvious STDs, and paying attention to cleanliness and hygiene when using public bathrooms, etc. Negative measures include the use of condoms, and regular STD screenings for high-risk groups, such as homosexuals and those who have a penchant for prostitutes, and courageous acceptance of treatment in the case of unfortunate illnesses. It is very important that sexual partners receive treatment at the same time. Cao Qingke, Department of Dermatology, Jiaxing No. 1 Hospital Error 1: Oral sex will not be infected with sexually transmitted diseases Oral sex is one of the most important ways to transmit sexually transmitted diseases, vesicles, gonorrhea, syphilis, nongonococcal urethritis, and AIDS may be infected through oral sex. Mistake 2: As long as you use a condom, you will not be infected with STDs Although condoms are the best way to prevent STDs, they are not foolproof, as improper use of condoms (e.g., not fully inserted, used only halfway through intercourse, and continuing to have intercourse after ejaculation, etc.) or poor quality of condoms ruptured in the midway of sexual intercourse, there is still a chance of contracting STDs. Mistake 3: Taking vitamin C before sex can prevent STDs Vitamin C does not have the function of preventing STDs. Mistake 4: In the urethra irrigation gasoline can cure urethritis gasoline not only sterilization function, but will hurt the mucous membrane of the urethra, causing serious tissue reaction. Mistake 5: Immediately after prostitutes urinate will not get sexually transmitted diseases The bacteria or viruses that cause sexually transmitted diseases will penetrate deep into the tissues or enter the bloodstream in a short period of time, so the effect of urinating immediately after sexual intercourse on the prevention of sexually transmitted diseases is quite limited. However, female patients urinate after sexual intercourse to empty the bladder of bacteria, which has the effect of preventing acute cystitis.