What Causes Crow's Feet? The Real Reasons Behind Them

What causes crow's feet? Mostly three things working together: very thin skin at the outer corners of your eyes, a ring of muscle underneath that pulls in every time you smile or squint, and years of sun. Genes decide how early that adds up to lines you can see. Smiling isn't the problem. It's just the movement the skin records.

Below we go through each cause, when crow's feet usually start, how to tell a line that comes and goes from one that stays, and what actually helps the area look smoother.

Why the corners of your eyes crease first

Start with the skin. The skin around the eyes is the thinnest on the face. In one study of 10 cadaver heads, researchers measured skin at 39 points across the face and found the thinnest dermis, the thick middle layer, on the eyelid: about 0.76 mm, against nearly 2 mm on the lower side of the nose. That's from a 2015 paper in Aesthetic Surgery Journal.

Now the muscle. A ring of muscle circles each eye and contracts when you smile, laugh or squint. At the outer corner, that pulls the thin skin into folds that fan outwards. Anatomists call it the orbicularis oculi. You'll just know it as the reason your eyes crinkle in photos.

Thin skin plus a muscle you use all day is why this is often the first place lines show.

What causes crow's feet: the main factors

Smiling and squinting

Every smile that reaches your eyes folds the skin at the corners along the same lines. The Cleveland Clinic describes crow's feet as fine lines caused by tiny muscles contracting at the outer corners of the eyes as you feel different emotions. Squinting in bright light adds more folds, which is why people who spend a lot of time outdoors often notice them earlier.

Sun exposure

Sun is the cause you have the most control over. UV light wears down collagen, the protein that keeps skin smooth, and bright sun makes you squint as well, so it works on the area twice. The Cleveland Clinic recommends SPF 30 or higher and sunglasses or a wide-brimmed hat to protect the area.

Collagen changing with age

As the Cleveland Clinic puts it, collagen naturally breaks down as you age. Less collagen means skin that springs back less well after each smile. That's what slowly turns a crease you only see mid-smile into one you see at rest.

Genes

Skin thickness, how your face moves and how your skin ages all vary from person to person and run partly in families. It's one reason two people with similar habits can get crow's feet a decade apart.

Smoking and dryness

The American Academy of Dermatology says smoking greatly speeds up how quickly skin ages. Dryness is a smaller, more temporary factor: dry skin shows every fine line more sharply, and those lines soften once the skin is well moisturised.

When do crow's feet start?

There's no fixed age. According to the Cleveland Clinic, many people first notice them in their 30s, and some not until their 40s, depending on genetics and how they look after their skin. Others see a faint line in their twenties, usually one that only shows when they smile.

Try this in a mirror. Smile, then relax your face completely. If the lines vanish, they're what dermatologists call dynamic lines: they only exist while the muscle is working. If you can still see them with your face at rest, they're static lines. The skin has started to hold the fold.

Are crow's feet a bad thing?

Worth saying plainly: crow's feet come from smiling, and nobody should smile less to avoid them. Plenty of people like them. We wrote this because people search for the cause, not because lines are a problem that needs fixing.

If you'd like to slow how quickly smile lines settle in, the useful question isn't how to stop the movement. It's how to look after the skin that's doing the moving.

What helps the area look smoother

• Sunscreen right up to the outer eye area, every morning. It's the step with the most evidence behind it.
• Sunglasses outdoors. They block light and cut down on squinting at the same time.
• Moisturise, so dryness isn't making fine lines look deeper than they are.
• A retinoid, if your skin tolerates one. The Cleveland Clinic lists retinol among the options. Skin this thin can flake and sting, so start slowly.
• Copper peptides, if you want something gentler. More on these below.

Botox and other injections work on the muscle rather than the skin. They're medical procedures, so if you're curious, a qualified, licensed practitioner is the right person to ask.

Where copper peptides fit

GHK-Cu is a small peptide your body already makes, carrying a copper ion. In research settings it supports the skin's collagen upkeep. The most relevant study for this area: a 2018 review in the International Journal of Molecular Sciences reports that a GHK-Cu eye cream used for 12 weeks by 41 women with sun damage did better than a placebo cream and a vitamin K cream. Lines looked reduced and skin measured denser and thicker.

What it doesn't prove: that any product, ours included, will do the same, or that GHK-Cu prevents crow's feet. It's one formula, one group, one area. For targeted spots like this, the balm stick (0.5% GHK-Cu in a water-free balm that dries matte) lets you put a thin layer exactly where you want it. Keep it on the bone at the outer corner, away from the eye itself. Our guide to copper peptides for under-eye wrinkles covers how to use GHK-Cu around the eyes in detail.

Frequently asked questions

Does smiling cause crow's feet?

Smiling is part of it, because the muscle that crinkles your eyes folds the skin at the corners every time. But sun, collagen changes and genes decide how quickly those folds turn into lines you see at rest. Smiling less isn't a sensible fix. Protecting the skin from sun does more.

Can you get crow's feet in your 20s?

Yes. Faint lines that only show when you smile are common in your twenties, especially if you spend time in the sun or squint a lot. Lines that stay visible when your face is relaxed usually come later. If early lines bother you, daily sunscreen and sunglasses are the place to start.

What's the difference between crow's feet and under-eye wrinkles?

Crow's feet fan out from the outer corners and are driven mostly by smiling and squinting. Under-eye lines sit directly below the eye, where the skin is thin and dryness shows easily. They often appear together, and the same gentle approach suits both.

Do forehead lines have the same causes?

Mostly, yes: thin skin over a muscle you use a lot, plus sun and time. The muscle is different, and so is the habit, raising your brows rather than smiling. Our piece on why forehead wrinkles appear young goes through them.

The short version

Crow's feet happen because the skin at the outer corners of your eyes is very thin and sits over a muscle you use every time you smile or squint. Sun speeds things up, collagen changes with age, and genes set the pace. Wear sunscreen and sunglasses, keep the area moisturised, and if you want an active, choose a gentle one you'll use every day. For more on how GHK-Cu works, start with what GHK-Cu is.