Saliva may contribute to the transmission of sexually transmitted diseases. Some pathogens of sexually transmitted diseases can be transmitted directly through body fluids such as saliva. Common modes of transmission of STDs include blood-to-body fluid transmission, sexual contact, or vertical transmission from mother to child. For some STDs that can be transmitted through contact with bodily fluids, such as AIDS, the patient’s saliva and other bodily fluids may contain a small amount of the virus, posing a risk of spreading the disease. Also, when there are open wounds or skin breaks in the mouth, the chances of infection will also increase. However, when a patient is infected with a sexually transmitted disease that cannot be transmitted directly through saliva, the simple exchange of saliva and body fluids will not cause transmission of the disease. However, when there are ulcers or skin lesions in the mouth, there is also a possibility of blood exchange or infection, which can lead to the transmission of a sexually transmitted disease. Therefore, intimate behavior is generally not recommended when in contact with a person with a sexually transmitted disease. During intimate contact with a person with a sexually transmitted disease, prompt personal protection and regular screening are required.