Leeches entering the body from the digestive tract generally have no effect, but may cause gastrointestinal reactions, while entering from the body surface may lead to skin redness, swelling or bacterial infections and other conditions. 1. Through the digestive tract: leeches are a kind of mollusks, if you consume a small amount of leeches, they will be killed by the high acidity of the stomach acid, and then go through the digestive tract, and then excreted with the feces, and this situation will not generally cause too many side effects. However, if a large number of leeches are consumed, it will cause gastrointestinal dysfunction and gastrointestinal reactions such as nausea, vomiting, abdominal pain and diarrhea may occur. 2. Via the body surface: leeches will attach to wounds on the surface of the body, thus attaching between the epidermis and the dermis. This situation will lead to localized redness, swelling, heat and pain, etc. It is necessary to go to the hospital for examination to determine the location of the leech and timely removal. At the same time, leeches contain a large number of pathogens, easy to bring pathogenic microorganisms into the human body, resulting in bacterial infection. It is recommended to pay attention to self-protection in order to avoid leeches causing harm to the human body.