Normal lines are two lines that extend down the side of the nose and are an important sign of facial aging. The causes include skin laxity, subcutaneous fat atrophy, collagen loss, etc. With the increase of age, the degree of decrescent lines will gradually deepen, and the appearance will look older, which can cause different degrees of impact on patients’ life and social activities when serious. When filling the lines, if you choose an irregular institution or a person without medical qualification to perform the operation, it may lead to the following hazards: 1. If too much hyaluronic acid is injected, it may lead to facial deformation and accelerate skin aging, making the whole face stiff and uncoordinated in proportion, affecting the beauty; 2. If the facial nerve is damaged during the injection process, it may lead to adverse consequences such as lip twitching or uncoordinated facial expression; 3. If the operator does not pay attention to the injection technique when performing the injection, it may lead to vascular embolism caused by mistakenly entering the blood vessels and manifesting as skin necrosis; 4. If the operator does not have technical experience during the filling process and fills in the outside of the decrescent line, the decrescent line not only cannot be improved, but also may deepen. Therefore, when filling the decrescendo lines, candidates should choose a regular hospital and be operated by a professional doctor.