Beauty & FitnessSunscreen is the anti-ageing product. Everything else is second.
UV exposure drives most visible skin ageing. What SPF means, how much to apply (more than you think), and why reapplying matters more than the brand.
If you only ever buy one skincare product, make it sunscreen. Dermatologists have been saying this for decades and the reason is simple: most of what we call "ageing" on the face — fine lines, uneven pigmentation, loss of firmness, broken capillaries — is photo-ageing, caused by cumulative ultraviolet exposure rather than time itself.
What the evidence shows
The clearest demonstration is a four-and-a-half-year Australian trial in which adults were randomly assigned to either daily sunscreen use or discretionary use. The daily group showed measurably less skin ageing on standardised skin casts. Sunscreen doesn't reverse damage, but it stops the clock on a large share of it.
SPF, explained without the marketing
SPF measures protection against UVB, the wavelength that burns. SPF 30 blocks roughly 97% of UVB; SPF 50 blocks roughly 98%. That difference sounds small, but in practice higher SPF gives you a margin of safety because almost nobody applies the amount used in lab testing.
What SPF doesn't tell you is UVA protection — the longer wavelength that penetrates deeper and drives most photo-ageing. Look for "broad spectrum" on the label, or the UVA-in-a-circle symbol in Europe and the UK.
How much to use
The tested dose is 2 mg per square centimetre of skin. For the face and neck that works out to about a quarter teaspoon — often described as two finger-lengths of product squeezed along the index and middle finger. Most people apply between a quarter and a half of this, which cuts the real protection dramatically.
Reapplication beats brand
Sunscreen degrades in sunlight and rubs off with sweat and touching. If you're outdoors, reapply every two hours. If you're indoors by a window, a single morning application is usually fine. A mineral or chemical filter, a fancy brand or a supermarket one: the differences are far smaller than the difference between applying enough and not.
What to do this week
- Buy a broad-spectrum SPF 30 or higher that you actually like the feel of, because you'll only use what you'll tolerate.
- Measure out a quarter teaspoon once so you know what the right amount looks like.
- Put it next to your toothbrush and apply it every morning, cloudy days included.