Sunscreen, SPF 50+ to sunscreen pills.

The trial: "Randomized, controlled, community-based intervention" in Nambour, Australia, four arms of daily or discretionary broad-spectrum sunscreen crossed with 30 mg of beta-carotene or placebo, and the endpoint "change in microtopography between 1992 and 1996 … graded by assessors blinded to treatment allocation"; the result "The daily sunscreen group showed no detectable increase in skin aging after 4.5 years. Skin aging from baseline to the end of the trial was 24% less in the daily sunscreen group than in the discretionary sunscreen group (relative odds, 0.76 [95% CI, 0.59 to 0.98])", with the honest limitation that "power to detect moderate treatment effects was modest" (Hughes 2013). The product was the parent trial's "sun protection factor 15-plus sunscreen to the head, neck, arms, and hands" every morning (Green 1999) — a 15-plus applied at the trial dose, which a 50+ at the dose you use roughly reproduces (Ou-Yang 2012). The supporting study is weaker and points the same way: 32 people applying an SPF 30 to the face daily for a year improved on every photoaging parameter from week 12, with texture, clarity and mottled pigmentation 40–52% better at week 52 (Randhawa 2016). The mechanism sits in the basics drawer: UVA to the dermis, infrared-A switching on the collagenase MMP-1 in 80% of people (Schroeder 2008).

Strong, and consistently so: the wrinkles, sun damage, collagen loss, dull skin and decade guides all grade daily sunscreen strong on this trial. One randomised trial with a modest effect size and cancer endpoints behind it outranks every serum, supplement and device on this site; the reason it is not "very strong" is that there is only one, and the reason the effect is not larger is that the discretionary group in Queensland also used sunscreen, just not every day.

The keratosis trials: 588 Australians over 40 applied an SPF 17 or its base cream to the head, neck, forearms and hands for one summer; "the mean number of solar keratoses increased by 1.0 per subject in the base-cream group and decreased by 0.6 in the sunscreen group", with fewer new lesions (rate ratio 0.62), more remissions (odds ratio 1.53) and "a dose-response relation: the amount of sunscreen cream used was related to both the development of new lesions and the remission of existing ones" (Thompson 1993); a two-year double-blind trial in a high-risk Texas clinic found "the rate of appearance of new precancerous skin lesions was less for the treatment group" (Naylor 1995); in Nambour the keratosis count ratio over two years was 1.20 with daily use against 1.57 with discretionary use, "equivalent to the prevention of an average of 1 additional SK per person" (Darlington 2003). The cancer: squamous cell carcinoma tumours "significantly lower in the sunscreen group than in the no daily sunscreen group (1115 vs 1832 per 100,000; 0.61 [0.46-0.81])" (Green 1999), and "significantly decreased by almost 40% during the entire follow-up period (rate ratio, 0.62)" eight years after the trial stopped (van der Pols 2006). In the highest-risk group of all, 120 organ-transplant recipients, the 60 given a daily SPF 50+ had "8 new invasive SCC (0 vs. 8; P<0.01)" and keratosis counts of "89 vs. 273" after two years (Ulrich 2009). The 2016 Cochrane review, counting people rather than tumours, found only the Nambour trial eligible for the general population and graded its evidence low quality (Sánchez 2016) — the tier here rests on the tumour counts, the keratosis trials and the transplant study together.

Strong, as the sun damage guide grades it. For the person who already has a field of keratoses the row pairs with oral nicotinamide and with the field treatments — photodynamic therapy, 5-fluorouracil, the medium peel — that the sun damage guide grades; the sunscreen is what keeps them from coming back.

The trials: 68 melasma patients on 4% hydroquinone were randomised to a broad-spectrum SPF ≥ 50 with iron oxide or the same without; "at 8 weeks, the UV-VL group showed 15%, 28% and 4% greater improvements than the UV-only group in MASI scores, colorimetric values and melanin assessments" (Castanedo-Cázares 2014); a prospective randomised comparison found significantly fewer melasma relapses over six months with a sunscreen that also blocked short-wavelength visible light than with a UV-only one (Boukari 2015); in 42 women through five months of a southern French summer, the tinted SPF 65 (UVA-PF 35, visible-light protection factor 66) significantly reduced the colour difference between melasma and unaffected skin and the identical untinted formula did not, while the melasma index fell in both groups (Polena 2025). Prevention in pregnancy: of 185 women who used an SPF 50+ (UVA-PF 28) daily, "only five new cases of chloasma were noted, an occurrence of 2.7%, which is much lower than the 53% previously observed" by the same investigators (Lakhdar 2007). The physics: visible light pigments type IV–VI skin more darkly and durably than long-wave UVA (Mahmoud 2010), iron-oxide formulations "significantly protected against visible light-induced pigmentation compared to untreated skin or mineral SPF 50+ sunscreen in Fitzpatrick IV individuals" (Dumbuya 2020), and "for a sunscreen to protect against visible light, it must be visible on the skin" (Lyons 2021). The 2026 international Delphi consensus lists "photoprotection with broad-spectrum sunscreens as essential" ahead of hydroquinone (Sarkar 2026), and the evidence-based review of 113 melasma trials assumes it under every intervention (McKesey 2020).

Strong, as the dark spots guide grades it. For ordinary sun spots and post-inflammatory marks the visible-light story matters less and the daily habit matters as much; the serums guide grades the brighteners that go under it and the dark spots guide the lasers that go after it.

The trial measured "change in microtopography" on the hand (Hughes 2013) and applied the sunscreen "to the head, neck, arms, and hands", with the cancer analysis "based only on skin cancers that developed on sites of daily application" (Green 1999) — so the strong tier belongs to these sites first. The car: across 34 vehicles, the windscreen attenuated 99.25% of UVA and the driver's side window 88.78%, with the front side windows the weakest glass in most cars and mileage, not age, predicting how much got through (Axelson 2025); "laminated glass offers better UVA protection than tempered glass" and "window films can be applied to glass to increase UVR protection" (Almutawa 2013). The result on the skin: in a Mohs unit's year, 52.6% of skin cancers were on the left, with "significantly more malignant melanoma in situ on the left (31/42, 74%)" (Butler 2010), and the textbook image is a truck driver's face aged decades more on the window side (Gordon 2012).

Strong, as the aging hands, décolletage and neck guides grade it. The practical difference from the face is attrition: hands are washed ten times a day and the chest is dressed and undressed, so the rule is a tube by the sink and one in the car, and long sleeves in UPF fabric for the drive.

The trial follow-up: "Ten years after trial cessation, 11 new primary melanomas had been identified in the daily sunscreen group, and 22 had been identified in the discretionary group … (hazard ratio [HR], 0.50; 95% CI, 0.24 to 1.02; P = .051). The reduction in invasive melanomas was substantial (n = 3 in active v 11 in control group; HR, 0.27; 95% CI, 0.08 to 0.97)" — "Melanoma may be preventable by regular sunscreen use in adults" (Green 2011). The cohort: 1.5 million person-years and 722 melanomas; "sunscreen users reported significantly more sunburns and sunbathing vacations", and SPF ≥ 15 use against SPF < 15 use carried a hazard ratio of 0.67, with a population-attributable fraction of 18% (Ghiasvand 2016). The meta-analysis: 29 studies, 313,717 participants, "the overall meta-analysis did not show a significant association between skin cancer and sunscreen use (odds ratio (OR) = 1.08)", with the pre-1980s studies showing sunscreen users at more than double the risk and the association fading to nothing by the 1990s — confounding by exposure, the authors conclude, and "this systematic review does not confirm the expected protective benefits" (Silva 2018). The behavioural trials explain the confounding: higher-SPF users stayed in the sun longer (Autier 1999; Autier 2000). The risk factors sunscreen does not touch: sunbed use raises melanoma risk by 20% overall and 87% when started before 35 (Boniol 2012), and in skin of colour the commonest melanomas are on the palms, soles and nails, where "there are limited data on UV exposure and melanoma risk" (Brunsgaard 2023).

Moderate, one tier below the sun damage guide's combined sunscreen row, which folds the melanoma follow-up into the strong squamous-cell and aging evidence; graded on its own, the melanoma claim rests on 33 events in one trial and a cohort that points the same way. Nothing here argues against the habit — the same daily application is what produced the trial's numbers — only against believing the bottle does the whole job.

The coverage data: "application of moisturiser was significantly worse than sunscreen in terms area of the whole face missed (11.1% missed with sunscreen compared to 16.6% for SPF moisturiser)", "primarily due to decreased coverage of the eyelid regions (14.0% missed with sunscreen, 20.9% moisturiser)", and "participants to be unaware of their incomplete coverage" (Lourenço 2019). The lips: in eight Galician dermatology departments, "more than 90% of AC patients (370/408) had never used lip photoprotection" (Rodríguez-Blanco 2019); the risk factors for actinic cheilitis are fair skin (odds ratio 3.30), age over 50, cumulative and daily sun exposure, male sex, drinking and smoking, and in the pooled observational data "the use of sunscreen creams and caps/hats to protect against the sun were factors with no significant influence" — which is what a habit almost nobody has looks like in a case-control study (Rodríguez-Archilla 2021). The eyes: modelled ultraviolet doses to the facial, periorbital and ocular zones under three head positions found "least sun protection was provided by middle-sized sunglasses", goggles "almost 100% protection at all skin zones", large sunglasses highly effective, and "sunglasses do not totally block UVR and should be combined with additional protection means" (Backes 2019). The hat: "hats with a wide (greater than 7.5 cm) brim are necessary in order to provide reasonable protection factors (greater than 3) around the nose and cheeks", a baseball cap protects the nose and little else, and a flat cap "negligible protection at all sites apart from the vertex and forehead" (Diffey 1992).

Moderate here, where the crow's feet and lip lines guides grade sunscreen and sunglasses strong: those rows borrow the face-wide Nambour result for the skin around the eye and mouth, which is fair, while this row grades what is known about the sites themselves — coverage photographs, dosimetry and a case-control null. The instruction is the same either way: carry the sunscreen to the lash line and the vermilion, use a stick where a fluid stings, and put the sunglasses on before the squint.

The review: "UV light is implicated in all significant aspects of rosacea: skin inflammation, neoangiogenesis, telangiectasia, and fibrosis, and may even initiate rosacea. While the use of sunscreens is widely recommended, the literature on the impact of photoprotection in rosacea is scarce. Adequately formulated sunscreens could not only provide the required level of photoprotection, but may also help to mitigate the barrier dysfunction, neutralize facial redness (tinted sunscreens), and decrease inflammation and vascular dysfunction" — six original studies of sunscreen in rosacea, all showing symptomatic improvement with the right vehicle (Morgado-Carrasco 2021). The vehicle: patients with rosacea "are particularly susceptible to the irritation caused by sunscreen ingredients", and "appropriate protective ingredients, such as dimethicone and cyclomethicone in the vehicle, may prevent irritation from other sunscreen ingredients" (Nichols 1998). The panel's recommendation for inflammatory and sensitive skin is a formulation adapted to the dermatosis rather than a particular filter (Passeron 2021); the practical translation is a mineral or mineral-led SPF 50 in a silicone base, fragrance-free, with a green or beige tint if the flush is the complaint.

Moderate, as the facial redness guide grades it: no trial has randomised sunscreen against none in rosacea, and the tier rests on mechanism, surveys and small formulation studies. The redness guide carries the treatments — azelaic acid, ivermectin, the vascular lasers — that the sunscreen protects.

The trial: 458 children in grades 1 and 4 were randomised, and among the 309 white children analysed, "children in the sunscreen group developed fewer nevi than did children in the control group (median counts, 24 vs 28; P=.048)", with modelling suggesting "freckled children assigned to a broad-spectrum sunscreen intervention would develop 30% to 40% fewer new nevi" (Gallagher 2000); by site, the protection was "on intermittently sun-exposed body sites", the trunk above all (Lee 2005). The stakes: "an increased risk of melanoma was seen with increasing number of sunburns for all time-periods (childhood, adolescence, adulthood, and lifetime)" (Dennis 2008), and first sunbed use before 35 carries a relative risk of 1.87 (Boniol 2012). The infant skin: "the skin's barrier protection remains immature throughout at least the first 2 years of life" and "accumulation of UVR-induced changes in the skin may begin as early as the first summer of life" (Paller 2011).

Moderate, because a mole count is a surrogate and there is one trial; the melanoma logic behind it is as strong as anything on this page. Practically: under six months, shade, a brim and clothing rather than cream; from six months a mineral SPF 50 on what the clothes do not cover; and for teenagers, whose sunburns count as much as anyone's, the honest message is that a tan is not protection (Miyamura 2011).

The study: "Thirty-two subjects applied a broad spectrum photostable sunscreen (SPF 30) for 52 weeks to the entire face … all photoaging parameters improved significantly from baseline as early as Week 12 and the amelioration continued until Week 52. Skin texture, clarity, and mottled and discrete pigmentation were the most improved parameters by the end of the study (40% to 52% improvement from baseline), with 100% of subjects showing improvement in skin clarity and texture" (Randhawa 2016). The controlled data on regression are for keratoses, not wrinkles: "more remissions (odds ratio, 1.53)" over a summer of SPF 17 (Thompson 1993) and a lower keratosis count in Nambour (Darlington 2003). The randomised aging trial measured prevention, not repair — "no detectable increase" — and that is the claim the strong tier belongs to (Hughes 2013).

Emerging, and deliberately separated from the prevention row so that the strong tier is not read as a promise of reversal. The mechanism is real — skin that is no longer being damaged repairs some of what it can — and the reader who wants more than that is in the retinoids, peels and resurfacing guides, every one of which assumes this row is already in place.

The glass: "all types of commercial and automobile glass block the majority of ultraviolet-B; however, the degree of ultraviolet-A transmission depends on the type of glass. Laminated glass offers better UVA protection than tempered glass" (Almutawa 2013; Tuchinda 2006); measured across 34 vehicles, 99.25% UVA attenuation at the windscreen and 88.78% at the driver's side window (Axelson 2025). The skin: more cancers on the left in an American Mohs unit, 74% of melanomas in situ (Butler 2010), and the driver whose window side of the face carried 28 years of extra aging (Gordon 2012). The screen: a controlled study of melasma patients exposed to the blue light emitted by electronic devices found no worsening over the short term (Duteil 2020) — the visible light that pigments skin in the laboratory is delivered at solar irradiance, orders of magnitude above a screen (Mahmoud 2010).

Emerging, because no trial has randomised indoor sunscreen against none and the case for it is dosimetry plus a left-sided cancer pattern; that is enough for the commuter and the window seat, and nothing for the "blue-light" claim that the marketing row grades. A daily morning application already covers the office window; the car deserves its own tube and, for the long-distance driver, a film on the side windows.

The numbers: "there were no significant differences in the incidence of first new skin cancers between groups randomly assigned daily sunscreen and no daily sunscreen (basal-cell carcinoma 2588 vs 2509 per 100,000; rate ratio 1.03 [95% CI 0.73-1.46])" and "no effect on incidence of basal-cell carcinoma by sunscreen use" in the tumour count (Green 1999); "after prolonged follow-up, BCC tumor rates tended to decrease but not significantly" (van der Pols 2006); in transplant recipients, "11 BCC (2 vs. 9; ns)" (Ulrich 2009). The Cochrane review's low-quality-evidence verdict on keratinocyte cancer as a whole rests on the same trial (Sánchez 2016). Basal cell carcinoma's epidemiology — intermittent exposure and sunburn, much of it before adulthood — is the likeliest reason a 4.5-year adult habit did not move it, and a 30-patient DNA-repair trial in xeroderma pigmentosum that cut basal cell carcinomas from 5.4 to 3.8 a year hints at where the tumour's damage is done (Yarosh 2001).

Limited, for the specific claim, and stated plainly because the site's other guides quote the squamous-cell and melanoma numbers and a reader deserves the one that went the other way. The nicotinamide row is the evidence-based addition for someone who has already had a basal cell carcinoma.

The tan: skin repeatedly exposed to sub-burning UVA, UVB or both looked equally tanned, but "the melanin content and UV-protective effects against DNA damage in UVB-tanned skin (but not in UVA-tanned skin) were significantly higher", so "UVA tanning contributes essentially no photoprotection, although all types of UV-induced tanning result in DNA and cellular damage" (Miyamura 2011) — and sunbeds are mostly UVA. The sunbed: across 27 studies "ever use of sunbeds was associated with a summary relative risk of 1.20", rising to 1.87 for first use before 35, "a 1.8% increase in risk of melanoma for each additional session of sunbed use per year", and an estimated 3,438 melanomas a year in western Europe attributable to them (Boniol 2012). The burn: risk rises with the number of sunburns in every period of life (Dennis 2008). The behaviour: SPF 30 rather than SPF 10 meant 72.6 against 58.2 hours of holiday sun and no less sunburn (Autier 1999), and the dosimeter trial found sunscreen "tended to increase the duration of exposures to doses of ultraviolet radiation below the sunburn threshold" (Autier 2000).

Limited, in the sense the site uses for negative evidence. Sunscreen is not a licence: the trial-proven habit is daily protection of skin that is going about its day, not a tool for lying in the sun longer, and the tan that the holiday is for is the dose this whole guide is about avoiding.

The network meta-analysis: fourteen randomised trials of interventions against post-inflammatory hyperpigmentation after laser and energy devices; "intradermal tranexamic acid (TXA), topical corticosteroids, topical vasoconstrictors, oral TXA, and epidermal cooling were significantly more effective in reducing PIH incidence compared with sunscreen monotherapy … while sunscreen monotherapy was ineffective compared with placebo" (Wongdama 2026). The split-face trial: 59 patients of skin types III and IV after a picosecond laser, a sunscreen with an anti-inflammatory agent on one side and a plain one on the other; "sunscreen A caused a higher reduction of the brown score compared to the other side but there was no statistically significant difference" (Puaratanaarunkon 2022). On a retinoid, the sunscreen earns its place differently: adding a sunscreen to adapalene improved tolerance and post-acne pigmentation in a randomised comparison, with fewer patients scaling and stinging (How 2023).

Limited for "sunscreen prevents post-laser pigment", which is what the bottle is often sold for after a procedure; not limited for wearing it, which the healing dermis needs and every guide on this site assumes. The resurfacing, laser and IPL and dark spots guides carry the protocols — tranexamic acid, a short steroid course, cooling — that the evidence actually supports.