Collagen

Collagen molecules are far too large to travel into the skin from a cream — that is simply true, and any brand claiming otherwise is selling you something. What topical collagen actually does is sit on the surface and hold water there, which plumps fine lines and gives that bouncy, cushioned look within minutes.

That is a real effect, just a temporary one. Which is why collagen shows up most usefully in overnight wrapping masks and jelly creams, where several hours of occlusion does the work.

For firmness that lasts, pair it with peptides or retinal, which do reach the layers where collagen is actually made.