The hyaluronic acid injected in medicine is a purified component that will fuse with the original hyaluronic acid in the body after injecting into the forehead, thus the skin will expand and the forehead will flatten and augment, which is extremely safe and has a very significant effect. However, there are some risks associated with this procedure, mainly due to improper surgical operation. After hyaluronic acid forehead augmentation surgery, it is likely that there will be some slight redness, swelling, bruising and other phenomena temporarily, which can be recovered in a few days or so, and very few will have allergy or even infection, which may be related to inexperienced physicians, improper operation and unqualified aseptic operation. Therefore, it is recommended that candidates choose a more formal hospital as well as an experienced expert to avoid these adverse reactions to the greatest extent. In addition, hyaluronic acid forehead augmentation can occur if the injection is too shallow or if no attention is paid to sun protection after surgery, the pigmentation phenomenon can be reduced or disappeared by using a whitening mask 4-6 times after 1 month, and the pigmentation phenomenon can be reduced or disappeared by serious irradiation to the embolism in the blood vessels to appear skin necrosis, vision loss, brain infarction, which is life-threatening. As we all know, hyaluronic acid is not permanent and will be lost through the body’s metabolism, and the effect is likely to be affected. Nowadays, there are common hyaluronic acid on the market, such as large molecule, medium molecule and small molecule, and the maintenance time is different according to the molecular weight. Some molecules are smaller and may last less than a year; some molecules are larger and may last more than a year and a half, so hyaluronic acid forehead augmentation needs to be refilled after six months to a year.