How to use 1) When using to your face for the first time, please use 1 ~ 2 drops mixed with in cream or lotion instead of using directly the undiluted ampoule. If you fit well, you can use it as original ampoule only. 2) When using to another body part except for face, please use 1 ~ 2 drops and be absorbed for special care. 3) If you not fit well, you must quit the using this product. 4) You can use both day and night. 5) If you use excessive amounts, your skin is under a lot of stress. so, please use as little as possible.