collagen
Skin Ageing and Collagen: What Really Changes From Your 20s On
Why does skin start to look and feel different from your mid-20s on? Mostly, it's collagen. Skin ageing and collagen loss go hand in hand: the protein that gives skin its structure slowly thins, breaks up and gets replaced less efficiently. The sun speeds all of it up, far more than most people realise.
This article explains what's changing under the surface, the two kinds of ageing and how much each one matters, why collagen loss tends to speed itself up, what shifts after 35, and what actually helps, in order of evidence. Copper peptides come in near the end, in proportion.
Skin ageing and collagen: what's actually changing
The firm, springy part of your skin is the dermis, the thick layer under the surface. A 2019 review in the International Journal of Molecular Sciences puts collagen at about 75% of the skin's dry weight. Most of it is type I, the heavy structural kind, with a smaller amount of finer type III.
Collagen falls with age, and it's been measured. In a 1975 study in the British Journal of Dermatology, Shuster and colleagues measured forearm skin in a large group of adults. Skin collagen fell with advancing age, and thinner dermis went with less collagen. Women had less skin collagen than men at every age.
Collagen doesn't just shrink in amount. The 2019 review describes it becoming fragmented and coarse, like old rope. Elastin, the protein that lets skin spring back, degrades too. The result is skin that's thinner, less firm and slower to bounce back when you press it.
The two kinds of skin ageing
Dermatologists split skin ageing into two types that happen at the same time.
| Intrinsic ageing | Extrinsic ageing | |
|---|---|---|
| What causes it | Time and genes | Mostly sun, plus other outside stresses |
| What it looks like | Fine wrinkles, thinner skin | Deeper wrinkles, laxity, uneven pigment |
| Can you change it? | Not much | Yes, a lot |
That description of each type comes from the 2019 review. The bigger surprise is how much of visible ageing is the second kind. In a 2013 study of 298 women aged 30 to 78, Flament and colleagues compared sun-seekers with sun-avoiders and concluded UV exposure seemed responsible for about 80% of visible facial ageing signs.
Worth noting what that study was: Caucasian women, scored by experts from standardised photographs. The exact figure won't transfer to everyone. The direction will. Most of what we think of as skin ageing is sun damage, and sun damage is the part you can do something about.
Why collagen loss speeds itself up
A few loops make skin ageing a bit of a snowball.
The fibroblast loop
Collagen is made by cells in the dermis called fibroblasts. They grip the collagen around them, and that tension keeps them active. The 2019 review describes what happens as collagen fragments: fibroblasts lose their grip, shrink and collapse, and make less new collagen. Less collagen means more collapsed cells, which means less collagen.
The sun loop
UV light triggers enzymes called metalloproteinases, or MMPs, that cut collagen apart. The review walks through the chain: UV creates reactive oxygen molecules, those switch on signals inside skin cells, and those signals switch on the MMP genes. Every unprotected day adds a little more fragmented collagen, which feeds the first loop.
The signal loop
There's a third, smaller piece. Your body makes a copper-carrying peptide called GHK-Cu that's involved in tissue repair. A 2018 review by Pickart and Margolina reports blood levels of about 200 ng/mL at age 20 and about 80 ng/mL at 60. Whether that decline drives skin ageing or simply comes with it isn't known.
What happens decade by decade
There's no single age when collagen switches off. The figures you see quoted, like "1% a year from 25", are rough rules of thumb, and we couldn't find a solid source for the exact number. Here's the general shape, without false precision.
- Your 20s: collagen is near its peak, but sun damage is already accumulating. This is when sunscreen habits pay off most, even if you can't see why yet.
- Your 30s: the first fine lines around the eyes, and skin that takes a little longer to recover from a late night or a pillow crease. Our guide to building a skincare routine after 30 covers this decade.
- Your 40s and 50s: thinner skin, more visible laxity along the jaw and neck, and for many women a sharper change around menopause. More on that below.
Skin after 35: what shifts, and what you control
Nothing switches off on your 35th birthday. What changes with skin after 35 is the running total. Years of slow collagen loss and sun exposure start to show as lines that stay after you stop smiling, less bounce and a duller surface.
The American Academy of Dermatology separates the natural process, where with time everyone gets visible lines, from premature ageing driven by environment and lifestyle. By your mid-thirties both are in play. The second is the one you can slow.
Skin gets drier and less forgiving
Many people notice skin feels drier, stings more easily, or takes longer to settle after a bad reaction. Dry skin makes fine lines look deeper than they are. That's why moisturiser earns its place more at 35 than it did at 25.
Hormones start to shift for some people
The NHS says menopause usually happens between 45 and 55, though it can come earlier, and lists dry, itchy skin among the symptoms of menopause and perimenopause. The American Academy of Dermatology reports that skin loses about 30% of its collagen in the first five years of menopause.
For most people in their mid-thirties that's a later chapter, and we cover it in copper peptides and menopause. If your skin changes suddenly, or you think your hormones are shifting, your GP or doctor is the right person to talk to.
The habits that matter most
The AAD's list of ways to slow premature skin ageing is refreshingly unglamorous. Beyond sun protection, which comes first below:
- Skip tanning. The AAD suggests self-tanner instead.
- Don't smoke, and drink less alcohol.
- Cleanse gently and moisturise daily. Scrubbing strips skin.
- Drop products that sting. The AAD advises stopping irritating skin care products.
Notice what isn't on the list: a ten-step routine. Most of the gains come from protecting the collagen you have.
What actually helps, in order of evidence
- Sunscreen, every day. The strongest move by a distance, because it slows the kind of ageing you can change. The American Academy of Dermatology recommends broad-spectrum SPF 30 or higher.
- A retinoid, if you tolerate one. The American Academy of Dermatology notes that retinoids boost collagen and reduce fine lines and wrinkles. The catch is irritation, so start slowly and use them at night. Our comparison of copper peptides and retinol covers who suits which.
- A gentler collagen-supporting active. Copper peptides sit here. Smaller evidence base, much easier on skin. More below.
- A moisturiser that keeps your barrier comfortable. It won't change collagen, but dry, irritated skin looks older and tolerates actives worse. See how to repair a damaged skin barrier.
Where GHK-Cu fits in
If your body makes less GHK-Cu with age, putting some back on skin is a reasonable idea. In lab studies, it gets fibroblasts making more collagen and elastin and helps clear damaged collagen. We explain that mechanism step by step in copper peptides and collagen.
On people, the evidence is small. The best-known study, reported in the 2018 review, had 71 women with sun-aged skin use a GHK-Cu cream for 12 weeks. Their skin measured denser and thicker, with fewer fine lines. What it did: one formula, one group, 12 weeks. How it relates to us: adjacent, not our formula. What it doesn't prove: that topping up GHK-Cu reverses anything, or that another product will match it.
So we'd put it this way. A copper peptide is a gentle, sensible third step after sunscreen and, if you can manage it, a retinoid. We put 2% GHK-Cu in the serum for exactly that job.
Frequently asked questions
At what age does collagen start to decline?
Gradually through adulthood rather than at one age. Measurements show skin collagen falling with advancing age, and most people start noticing the effects in their late 20s or 30s. The pace depends heavily on sun exposure, which is why two people of the same age can have very different skin.
What happens to your skin after 35?
Nothing sudden. Collagen has been thinning slowly for years, sun damage has been adding up, and skin often gets drier and less forgiving. By the mid-thirties that usually shows as fine lines that linger and less bounce. Hormonal changes around menopause come later for most people and speed things up again.
Can you rebuild collagen you've lost?
Partly. Skin keeps making collagen all your life, and some topicals, retinoids in particular, can help it along. What you can't do is return to the skin you had at 20. The realistic goal is slowing loss and supporting what you make.
Does sunscreen really slow skin ageing?
Yes. It's the single most effective thing you can do for it. UV is the main driver of the ageing you can change, and one study put it at around 80% of visible facial ageing in the women it looked at. Daily broad-spectrum SPF 30 or higher is the baseline.
The short version
Skin ageing is mostly a collagen story. Collagen thins and fragments with time, and the sun accelerates that far more than time alone. The damage feeds itself, which is why protection matters early, and by 35 the running total starts to show. Sunscreen comes first, a retinoid second if you tolerate one, and a gentle collagen-supporting active such as GHK-Cu after that. For the full evidence on copper peptides, read our scientific review of GHK-Cu.
