The serum and ampoule are added after toner or essence, if such is included in the skin care routine. The serum and ampoule are always added before face cream.
The serum is added after the toner and essence, before the moisturizer. If you are using several serums and/or ampoules at the same time, add them from a more liquid consistency to a thicker one.
The Ampoule contains active ingredients in high concentrations, which are intended to treat a specific skin problem, such as uneven skin tone or lines. Ampoules often contain only one active ingredient, such as centella, but in higher concentrations than in serum.