On clean skin, apply on areas of the face, neck and/or upper chest in the AM and/or PM. For day use, follow with a preferred SPF. For more photosensitive or reactive skin types, apply serum in the PM.
Note: It is a common side effect due to the high concentration of L-ascorbic acid to notice mild irritation and redness, flaking of the skin, and/or even tiny red bumps. The ingredient, Vitamin E, may exacerbate an already oil-prone condition. Modify the use of serum by using fewer pumps and/or using it on fewer days until the skin has become acclimated to it.