The dermis is the thick, collagen-rich layer of skin located just beneath the visible epidermis, and it’s where nearly all of skin’s collagen actually exists.
When people talk about “collagen in the skin,” they’re really talking about one specific layer: the dermis. It’s not visible, and most of us never think about it directly, but it’s the layer doing almost all of the structural work that determines how skin looks, feels, and ages.
The Three Layers of Skin
Skin is made up of three layers. The epidermis is the thin, outermost layer we can see and touch, mostly responsible for protection rather than structure. Beneath that sits the dermis, a much thicker layer built primarily from collagen, elastin, and a network of blood vessels, nerve endings, and hair follicles. Below the dermis is the hypodermis, a fatty layer that provides cushioning and insulation. Of these three, the dermis is where the story of skin aging really unfolds.
Dermis Collagen: What the Dermis Is Actually Made Of
The dermis is composed of two sub-layers: a thinner papillary layer close to the epidermis, and a much thicker reticular layer beneath it. Together, these layers are roughly 70 to 80% collagen by dry weight, primarily type I and type III collagen, along with elastin fibers and proteoglycans that help the tissue hold water.¹ This collagen is produced and maintained by fibroblasts, specialized cells that live throughout the dermis and continuously build new collagen while clearing away older, damaged fibers.
This composition is what gives the dermis its two defining physical properties: firmness, from the density of the collagen network, and elasticity, from the way collagen and elastin fibers are organized and interconnected.
Unlike some other collagen-dependent tissue in the body, the dermis has a relatively good blood supply, which means it has more capacity for repair and renewal than tissue like cartilage. This is actually good news: it means the dermis remains responsive to support well into midlife and beyond, rather than being locked into a fixed trajectory of decline.
Why the Dermis Matters More Than the Epidermis
The epidermis gets renewed roughly every month, but it has very little to do with the visible signs most of us associate with aging, like sagging, fine lines, or a loss of firmness. Those changes originate in the dermis, where collagen turnover happens much more slowly and where the real structural decline occurs over years, not weeks.
This is a big part of why topical products have a limited ceiling for how effective they are. Most skincare formulas work on the epidermis and, at best, reach only the uppermost portion of the dermis. Meaningful, lasting changes to the dermis’s actual collagen content depend on what’s happening inside the body, not what’s applied to the surface. This distinction is why healthy aging should start with structural health, not skincare.
How Dermis Collagen Changes With Age
The dermis naturally thins with age as fibroblast activity slows and collagen turnover becomes less efficient. This process accelerates sharply during the menopause transition. Research tracking skin collagen directly has found losses of close to 30% in the first five years after menopause, with continued yearly losses of around 2.1% for at least a decade after that.² This decline is driven largely by estrogen, since estrogen receptors sit directly on the fibroblasts responsible for maintaining the dermis, and declining estrogen during perimenopause and menopause weakens the signal that keeps those cells actively producing new collagen.³
Collagen Peptides for Skin Elasticity: Why Support Has to Start From Within
Once you understand that the dermis, not the epidermis, is where skin’s real structural health lives, it becomes clear why supporting collagen from within matters so much. Clinical research on specific bioactive collagen peptides has shown measurable improvements in skin elasticity and hydration within 8 to 12 weeks of daily use, working through the same collagen-building pathway the dermis has relied on all along.⁴ The dermis is, quite literally, where skin lives. Supporting it directly, rather than only managing what sits on top of it, is the foundation of real structural skin health.