The effect of hyaluronic acid is between 7- 10 months, and it takes several injections of hyaluronic acid to maintain the effect. Long-term injection of hyaluronic acid is completely harmless to human body. Introduction: Hyaluronic acid originally exists in human skin and is a natural moisturizing component of human body. People's skin begins to age after the age of 25, and the hyaluronic acid contained in the skin will gradually lose. Appropriate supplementation of hyaluronic acid to human skin can enhance the ability to retain water for a long time, and it will be integrated with the human body without any harm after injection.