Lately, my skin has been missing its usual glow, the kind of everyday dullness a good night’s sleep and a little extra water can’t quite fix on their own. So, I decided to put Kiehl’s brand-new 1cc CollaShot Plumping Serum ($78) to the test alongside its cult-favorite Micro-Dose Anti-Aging Retinol Serum ($95), pairing a plumping serum with a retinol serum to build a more complete, well-rounded routine.
Ahead, a closer look at what each serum brings to the table on its own and how using them together has changed the way I think about layering my routine.
The Benefits of Layering Collagen and Retinol
CollaShot is the newer of the two, and it is impossible to miss on the shelf: a bright pink gel-serum that gets its color from vitamin B12. The pink is a bonus, but the real story is recombinant collagen polypeptides in a supra-liposomal delivery system, engineered to reach up to 10 layers into the skin’s surface. In an eight-week clinical test, cheek sagging improved by 22 percent among consumers on a GLP-1 for weight loss, and 93 percent of consumers agreed skin looked plumper overall. It is a fast, watery texture that sinks in almost instantly.
The Micro-Dose Retinol Serum is the quieter powerhouse. It is formulated with pure retinol at a daily-strength micro-dose, plus peptides and ceramides to keep the barrier calm, which is why it is gentle enough for first-time retinol users and sensitive skin. “The precise dose of retinol can then be effectively delivered into skin to begin providing benefits without over-accelerating cell turnover or disrupting the skin barrier,” says Kiehl’s global scientific director Nancy Ilaya, PhD. In a 12-week clinical evaluation conducted by Kiehl’s, 100 percent of users showed reduced fine lines and wrinkles and 90 percent showed improved firmness.
Used back-to-back, the logic tracks with how dermatologists recommend layering skin care in general. (Thinnest formulas go first, richer ones follow.) CollaShot’s plumping serum goes on first to address volume and immediate bounce, then the retinol serum follows to work on texture and turnover over time—one addressing how skin looks right now and the other addressing how it rebuilds itself. Together, they cover more ground than either would solo, especially for anyone managing the kind of collagen and volume shifts that come with rapid weight loss.
As GLP-1 medications have become more common, dermatologists have been seeing a related pattern in skin. Rapid fat loss can leave the face looking less supported because cheek volume relies on both fat and the skin’s own collagen network. That’s part of why collagen-focused formulas like this one have become such a talked-about category this year. Dermatologists point to them as a useful, noninvasive piece of the puzzle for skin going through GLP-1-related changes, even though a serum alone can’t replace what's been structurally lost. But, you don’t need to be on a GLP-1 to feel the appeal. Collagen support is collagen support, whatever’s behind the dullness or loss of bounce in the first place.
The Bottom Line
My skin has looked noticeably more awake since I started using these two products, and that's really the only test that matters to me. I'm not chasing dramatic before-and-afters, just consistent, everyday improvement. CollaShot and the Micro-Dose Retinol Serum have delivered that, which is why they've both earned a permanent place in my routine.
