The main reasons are as follows: 1. The disease itself has no special medicine or is difficult to be cured, such as AIDS; 2. The treatment is irregular, or the course of treatment is too short and incomplete. Many patients do not receive regular and effective treatment at the early stage of the disease, they do not go to the hospital, but go to the pharmacy to buy their own medicine or go to the street doctors or irregular hospitals for treatment, so that the disease is delayed and becomes chronic or uncontrollable; 3, sexual partners with STD infection do not receive effective examination or treatment, resulting in re-infection with STDs. Therefore, the sexual partners of STD patients should be examined or treated even if they have no symptoms. If there is a high suspicion that they are infected with a treatable STD, they should be treated with medication even if they are asymptomatic or until a laboratory report is available. Sexual activity should be prohibited during the illness; 4. Untimely or incorrect laboratory reports. Correct and timely laboratory test reports are an important basis for clinicians to make the correct diagnosis and treatment. If the reports are not timely or accurate, they will affect the development of treatment plans or prognosis, especially when multiple STD co-infections occur; 5. Some pathogenic microorganisms of STD infections will mutate and drug-resistant strains will appear, therefore, where available, culture and drug sensitivity tests of pathogenic microorganisms should be performed to find out sensitive antibiotics; 6, when STD patients have multiple microbial infections, there is no joint application of drugs for multiple specific pathogenic microorganisms, such as drugs for gonococci only, but not drugs for killing mycoplasma and chlamydia The pathogens are not completely eliminated. This situation is likely to occur in the laboratory report before the treatment, or not at all when the laboratory tests; 7, the body resistance is poor, antibiotics alone is difficult to completely kill the pathogenic microorganisms, or there is no effective drugs to kill, only temporary inhibition, to be the body resistance is weak when out of activity, such as genital herpes. The STD lesions are difficult to remove completely at once, and the residual lesions are prone to recurrence, such as condyloma acuminata. Or repeated use of a large number of broad-spectrum antibiotics lead to dysbiosis in the body, the emergence of conditional pathogenic bacteria infection in the original STD infection site, aggravating the clinical symptoms; 8, local infected tissue antibiotics difficult to achieve effective bactericidal concentration. When some parts of repeated STD infections or chronic infections form scars, tissue hyperplasia, etc., so that the drugs used is difficult to achieve effective bactericidal concentration in the site, affecting the efficacy; 9, STD sites such as the female genitalia there are conditions conducive to the growth of microorganisms, such as the placement of birth control rings, etc., making it difficult to complete treatment, causing relapse; 10, mental illness. Although some patients have been cured of STD, but due to the fear of STD, so that always think that there is no good, a little discomfort is considered to be an attack of STD, often run to the hospital, and even ask the doctor to apply certain drugs to him (her) often. Such patients can seek help from psychologists in addition to good clinical explanation.