The hard pack after chin hyaluronic acid is related to hyaluronic acid not absorbed, incorrect injection level, postoperative infection and other factors. 1. Hyaluronic acid is not absorbed: hyaluronic acid injected into the chin belongs to large molecule hyaluronic acid, which is relatively viscous, and it is not easy to be absorbed when it is injected into the chin, when hyaluronic acid is not absorbed by the human body, a hard bag will appear in the chin. This is a normal phenomenon after the injection of hyaluronic acid, injection of hyaluronic acid within 24-48 hours can be appropriate ice. 2. Incorrect level of injection: hard packs of hyaluronic acid after chin injection may be incorrect with the level of injection, the injection does not grasp the position, it is easy to appear hard packs and other adverse reactions after injection. 3. Post-operative infection: hard packs of hyaluronic acid after chin injection may be caused by the irregularity of hyaluronic acid injection products or the lack of post-operative care, which may lead to infection after injection. In order to avoid the occurrence of hard packs after chin hyaluronic acid, it is recommended that when candidates need to inject hyaluronic acid in the chin, they should go to regular hospitals and let experienced doctors to operate. If there is any discomfort, please go to the hospital in time.