That depends on whether both sides have venereal diseases, kissing the depth of intensity, whether the two sides mouth damage, etc. in foreign countries in a short time followed by kissing with the same icon, while the occurrence of cases of syphilis infections lips.
This is largely determined by whether it was survival of pathogens, whether close contact.
In general, the kissing disease is not contagious, but under exceptional circumstances, but also can be infectious diseases, why do you say? Is because if there is such a mouth that kind of damage, there are gaps in this case, if there are other sexually transmitted diseases, this time by oral pathogens enter the body in the gaps, it is sometimes kissing can spread diseases, including sexually transmitted diseases, . Therefore this problem, we can not simply understand it, under normal circumstances, 99% is not infectious, but there may be 1% on the infection in this way. Of course, this approach in clinical practice is extremely rare, at least for now I do not see through the mouth and kissing to spread sexually transmitted diseases, general infectious diseases mainly oral sex, oral communication, with a simple kiss may still not the same.
Overall, the general kissing (courtesy, sociability) is a relatively safe, while deep-kiss (both sides have exchanged saliva, and even bleeding) are possible adoption of certain body fluids (blood) spread of sexually transmitted diseases (such as syphilis , AIDS) is concerned, there is a certain risk.