It is not recommended to have oral sex during the cold. Because of the low resistance during the cold, it is very easy to occur in the corners of the mouth blisters, mouth ulcers, etc. If oral sex is performed at this time, it is easy to cause bacteria and viruses to enter the mouth, which can aggravate the symptoms of the cold, or cause other diseases, such as acute or chronic periodontitis. In addition, it is also possible to pass the cold to each other through oral sex, or cause each other to appear genitourinary system infections. Usually oral sex must pay attention to oral hygiene and peri-genital hygiene, if there is oral disease or the other party has the possibility of STDs, try to avoid oral sex.