Does sunscreen slow skin ageing? What a randomised trial found

When does protection matter in the UK?

The NHS identifies roughly 11am–3pm from March to October as the strongest UK sun and advises considering protection when the UV index is 3 or above. Use shade, clothing and sunscreen together. For sunscreen, it recommends at least SPF 30 and four-star UVA protection; SPF and the UVA rating describe different aspects of protection.

Checking the UV forecast gives you more useful information than judging by warmth alone. Think about the exposed skin and time outside as well: a short shaded trip, a long walk and an afternoon's outdoor work are different situations. A brimmed hat and sleeves can cover areas you would otherwise need to protect with product.

The British Association of Dermatologists says year-round sunscreen is unnecessary in the UK for most people, because winter UV is generally too low. Certain medical conditions are exceptions. If a clinician has given you individual photoprotection advice, follow it.

Location changes the answer. The Met Office explains that altitude and reflection from snow can increase UV exposure, so a winter skiing holiday is not the same as an ordinary winter day at home. A daily cosmetic SPF habit is a choice, but these trials do not measure a universal UK winter anti-ageing benefit.

How much should you use, and when should you reapply?

The NHS suggests about 6–8 teaspoons for an adult's whole-body coverage. If you expect to remain out long enough to risk burning, it advises application 30 minutes before leaving and again just before going out. Thin coverage gives less protection than the label suggests.

For a smaller exposed area, Cancer Council Australia gives approximately one teaspoon for the face, neck and ears together. That is an area-specific practical guide; a teaspoon for those three areas should not be misquoted as a teaspoon for the face alone.

American Academy of Dermatology guidance highlights commonly missed exposed areas, including ears, neck and the tops of feet, and advises reapplying every two hours outdoors and immediately after swimming or sweating. The NHS also advises reapplication after towel drying or rubbing off, following the product instructions.

Check the expiry information as well as the protection rating. The NHS explains that the open-jar symbol gives a number of months after opening. Marking the opening date on the container helps you check that limit when bringing out a partly used bottle.

Choose a texture you can spread across the required area without routinely skimping. If a product stings or causes a reaction, seek advice about an alternative. When comparing products, first check protection and whether you can use the directed amount. Extra cosmetic ingredients answer a separate question.

Consider an actual outing: the face and neck may be protected when you leave, but removing a jumper later exposes the arms. Reapplication also needs to fit the time you are outside, not just the time you originally expected to stay. Keep the product available for that change of plan, and use clothing or shade when application is impractical.

What did the long-term sunscreen trial show?

The 2013 Nambour trial included 903 eligible Australian adults younger than 55. Researchers used silicone replicas from the back of the left hand, with blinded grading. Higher grades represented a flatter surface with deeper horizontal lines and fewer fine vertical lines.

The daily-use group had no statistically detectable increase in the adjusted analysis; this does not mean every person's skin was unchanged. The clearest comparison was between groups: relative odds of higher ageing grades were 0.76, with a 95% confidence interval of 0.59–0.98. That corresponds to 24% lower relative odds, with uncertainty spanning roughly 2%–41% lower. This includes a very small effect.

There were missing measurements: 604 participants supplied usable replicas at both time points. The outcome was graded skin texture on the hand, not facial wrinkles. Regular use was compared with discretionary sunscreen use, not enforced avoidance of sunscreen.

What does 24% lower odds actually mean?

The 24% figure is a relative difference in odds across the study's grading scale. It is not 24 fewer wrinkles in every 100, 24% younger skin, or 24 percentage points subtracted from an individual's risk.

A simple calculation shows why odds and probability differ. If an imaginary binary outcome affected 50 of 100 people, its odds would be 50 divided by 50, or 1. Multiplying by 0.76 gives 0.76, which converts back to a probability of about 43%. Subtracting 24 percentage points from 50% would instead give 26%, which is the wrong operation. This example explains the arithmetic; it does not reconstruct the trial's multi-grade analysis.

For a person choosing daily care, the decision does not require a forecast of exactly how their face will change. It requires a reasonable expectation of benefit, a product they can use and a routine that fits their exposure. The trial provides evidence for prevention, while its measurements define the limits of that evidence.

Was there a benefit for facial skin too?

A 2023 randomised study followed 290 Brazilian women for a year. A specified SPF 60 product used twice daily was compared with usual skincare. Fifteen dermatologists graded standardised photographs without knowing the treatment allocation. Four selected facial signs, including forehead wrinkles and dark-spot size, worsened less; four other comparisons were not statistically significant.

Participants covered Fitzpatrick phototypes II–VI. This scale describes typical burning and tanning responses, rather than ethnicity: the range extends from skin that burns easily and tans little to more deeply pigmented skin that burns less readily. The NHS Fitzpatrick chart explains the terminology.

The product group reported about 153 minutes of daily sun exposure versus 123 with usual care. Individual phototype groups were too small for confident separate conclusions, although broader pooled comparisons were reported. L'Oréal funded the study; several authors were employees and other financial relationships were disclosed.

These details matter when comparing a manufacturer's summary with the paper. The study supports some facial benefits from that product and routine. It does not show that every facial sign improved or identify which ingredient accounts for the difference from usual care.

What did the newer microscopy study add?

An August 2026 paper reported a year-long Paris trial with 59 women analysed, aged 55–65. It compared a daily UV-filter formula with a cosmetically similar vehicle without those filters. The active formula had SPF 10.3 and enhanced UVA protection; both groups received SPF 50 for unusually high intentional exposure.

Microscopy found a between-group difference in seasonal melanin-density changes. A separate dermal ageing index changed significantly within the vehicle group but not within the protected group; however, the analysis comparing those changes between groups found no effect. Different within-group significance is not proof that the treatments differed on that index.

The participants had phototypes II–III, a restricted lighter, sun-sensitive range. L'Oréal supported the work, and the authors were employees or a consultant. This adds evidence about pigmentation under specific conditions, but does not establish fewer visible wrinkles, longer life or a benefit from routine UK winter use.

What if you want to treat existing lines or pigmentation?

Someone choosing skincare may want to prevent future UV-related changes, treat acne, address pigmentation or change the appearance of existing lines. One positive prevention trial cannot settle all of those aims.

Research on retinol and tretinoin concerns different interventions, populations and outcomes. If existing lines or pigmentation are the main concern, that evidence asks a different question from whether sunscreen slows future change.

You can keep time outdoors while accounting for UV. Our guide to daylight and the body clock discusses timing light exposure for sleep; that does not require sunburn or looking directly at the sun. The practical tasks are compatible: choose the time and activity, then protect exposed skin according to the conditions.

A new or changing lesion needs assessment

The NHS melanoma guidance advises seeing a GP for a mole that changes size, shape or colour, or becomes painful, itchy, inflamed, bleeding or crusty. A sunscreen purchase does not assess such a change.

The NHS non-melanoma skin-cancer guidance also advises review for a growing or changing skin growth, or an area that hurts, itches, bleeds, crusts or scabs for more than four weeks. These symptoms do not establish cancer, but they deserve checking rather than being labelled ordinary ageing.

Make a note of what changed and when so you can describe it clearly. Do not delay seeking advice while trying several cosmetic treatments to see whether the appearance improves.