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As an editor and writer covering skincare, hair, makeup, and fragrance for almost 23 years, I’ve developed a nose for beauty products. When your inbox fills with thousands of product pitches a week, and you’ve sat through hundreds of presentations on the latest “breakthrough ingredient,�� you become a bit discerning, if not jaded.I can't tell you how many times I've heard about some plant-based ingredient plucked from the top of a snow-covered mountain where nothing else grows being touted as The Next Big Thing. Until the next bigger thing comes along, scooped up from the bottom of the ocean.It’s not that I don’t believe in innovation or plant-based ingredients—I like and use many—it's just that I also believe in science. And more often than not, there's little peer-reviewed research to support most brands�� hefty claims. So, when friends and family corner me at a party and ask, “What really works?�� they’re often surprised and disappointed to hear my unglamorous short list—or my favorite answer, sunscreen.Related video above: Do expensive sunscreens really work better?Of course, a reporter is only as good as her sources. Fortunately, mine are pretty good: clinical data and the people who study and work with skincare ingredients every day—dermatologists and cosmetic chemists. So, let’s go straight to those sources, shall we? Here are the skincare ingredients with solid research to prove they really deliver results. SunscreenThere’s no dispute here: SPF works. In the U.S., sunscreen filters are regulated by the United States Food and Drug Administration as over-the-counter drugs. “That means the ingredients used, which include mineral-based zinc oxide and titanium dioxide and 14 chemical filters, have been scrutinized by the FDA, with rigorous scientific evidence showing they protect against both ultraviolet (UV) A and UVB rays,�� says Ivy Lee, M.D., a dermatologist in Los Angeles and chair of the Augmented Intelligence at American Academy of Dermatology (AAD).Widely accepted research shows that sunscreen protects against skin cancer, with two significant studies showing that using sunscreen with SPF 15 daily reduces squamous cell carcinoma by 40 percent and melanoma by 50 percent. These large-scale, long-term studies led by renowned cancer epidemiologist Adele Green date back to the 1990s in Australia (where there is high UV and an increased risk of skin cancer). “Australia has led the world in sunscreen research; there haven’t been any significant studies since these,�� says cosmetic chemist Perry Romanowski. “There’s not a huge incentive to spend a lot of money on researching something that everyone already believes works.�� Aside from its skin cancer-protective benefits, there are aesthetic reasons to be an SPF devotee, as well. In 2013, Green and her team found that regular SPF use can slow the visible signs of aging. In that study, published in the Annals of Internal Medicine, 903 adults between ages 25 to 55 were assigned to use broad-spectrum sunscreen (which protects against both ultraviolet (UV) A and UVB rays) daily or at their discretion. Those who wore it daily were 24 percent less likely to show increased aging, including fine lines, sagging, and hyperpigmentation.What to look for: Because it's subject to strict regulation, finding a sunscreen that works is easy. In general, look for the words “broad-spectrum�� on the label. And while the studies were all done with SPF 15, the AAD now recommends SPF 30 for everyday use. “Compliance is a tremendous issue, as is the fact that people don't generally wear enough to get the protection listed on the label,�� says Romanowski. So, starting with SPF 30 means you should get enough coverage, even if you don’t apply quite enough of it. See below for a selection of sunscreens recommended by Women's Health editors for a variety of skin types.Retinoids These vitamin A derivatives have long been the gold standard for acne and skin aging—and for a good reason. “Retinoids bind to retinoic acid receptors in the skin, promoting cell turnover, increasing collagen and elastin production, improving acne, and reducing fine lines and wrinkles,�� says Dr. Lee. The majority of the available scientific literature focuses on prescription retinoids, which are considered the most potent. Over-the-counter versions, available in skincare products like serums and moisturizers, are considered cosmeceutical ingredients, actives that have a “drug-like�� effect on the skin. They include retinol, retinaldehyde, retinyl palmitate, retinyl propionate, retinyl acetate, retinyl retinoate, retinyl N-formyl aspartamate, and adapalene.Of all cosmeceutical retinoids, retinol is the most studied via randomized, double-blind, vehicle-controlled clinical trials (read: quality studies), according to a 2022 review in Advances in Therapy. The paper notes that retinol is ten-fold less potent than prescription tretinoin, but that doesn’t mean it’s ineffective. It has been shown to increase skin's production of hyaluronic acid, collagen, and elastin, and increase cellular turnover. In a 2020 12-week, double-blind, controlled clinical trial, researchers compared three retinol serums (0.25%, 0.5%, 1.0%) to prescription tretinoin creams (0.025%, 0.05%, 0.1%) using a step-up protocol to increase the strength applied. The retinol formulations performed just as well, if not better, than the tretinoin creams.The review also looked at adapalene, which is known as a third-generation retinoid. It binds to receptors more specifically than earlier retinoids, reducing the amount of irritation. Adapalene was once available only with a prescription but is now sold OTC (it's the active ingredient in Differin). Because of that, Romanowski says it has some of the best evidence of being effective for acne and for skin aging when used off-label. In one six-month study, adapalene significantly improved the signs of aging, including a 40 percent reduction in forehead wrinkles. What to look for: “The challenge with OTC products is that sometimes we don’t know what the retinoid derivative is or its percentage of a formula,�� says Dr. Lee. Most retinol formulations max out at 1 percent, which is considered an effective concentration. In terms of which retinoid to look for, Dr. Lee says that type isn't as important as the concentration. She suggests using one full bottle and reassessing your skin before increasing the strength or moving to a different retinoid. Again, we've got some great picks for you here.Niacinamide Niacinamide, also known as vitamin B3, is a do-it-all ingredient that isn’t irritating and plays nice with other ingredients in a formulation. For that reason, all of our experts had it on their shortlist—and research confirms its superhero status. “Niacinamide strengthens the skin barrier, reduces inflammation, minimizes pores, regulates oil production, and improves hyperpigmentation,�� says Amy B. Lewis, M.D., clinical associate professor of dermatology at Yale University School of Medicine. A 2024 review published in Antioxidants notes that niacinamide penetrates the stratum corneum (skin’s thick, protective outer layer), affects skin cells and human skin and that peer-reviewed, double-blinded, placebo-controlled clinical trials have shown significant results to substantiate its many claims. In short: topical niacinamide has been proven to do what it’s supposed to do on human skin.It’s used in topical treatments for acne, melasma, eczema, rosacea, psoriasis, wrinkles, skin laxity, texture changes, sensitivity, and pigmentation, increasing ceramide and fatty acid production in the skin to strengthen the skin barrier, Dr. Lewis explains. It also throws a wrench in the pigment production process, reducing dark spots. “Clinical studies show 5 percent niacinamide can visibly improve skin texture and tone over eight to 12 weeks,�� she says. Interestingly, researchers still don’t know exactly how it works, but the studies show that it does.Because of its anti-inflammatory role, niacinamide is especially good for those who can’t tolerate topical retinoids or other harsh actives. In a small but well-designed study, niacinamide was compared to hydroquinone for melasma (brown patches induced by sun exposure and hormones). It yielded “good to excellent results�� in 44 percent of people compared to 55 percent of those on hydroquinone. Still, niacinamide also reduced inflammation, improved sun damage, and had fewer side effects than hydroquinone.What to look for: Most studies on OTC niacinamide used formulas with 2 to 5 percent concentrations, and research shows that water-in-oil formulations that mimic the skin barrier, such as serums, are best for getting through the skin’s outer layer. Our favorite serums are:Hydroxy Acids This ubiquitous category includes both alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs), both widely used exfoliants in skincare products (and professional peels). AHAs are a group of acids that all work similarly—they loosen up the intracellular glue that holds skin cells in place on the skin’s surface so they can slough off faster, revealing brighter skin. We know they work because you can see the results pretty quickly. “When you use something like niacinamide once, you won’t notice a difference; it takes at least a month,�� says Romanowski. “But when you apply an AHA, things peel off pretty quickly,�� he says. Glycolic acid and lactic acid are the most commonly used in skincare products. Other AHAs include malic, citric, tartaric, and mandelic acids. “Both AHA and BHAs have been clinically proven to treat acne, hyperpigmentation, and the signs of aging,�� says Dr. Lewis. BHAs, which include salicylic acid and lipo-hydroxy acid (LHA, patented by L’Oreal and used in La Roche-Posay and SkinCeuticals products), gently exfoliate but work differently. These are oil-soluble, which allows them to get into pores and dissolve sebum, making them good options for acne-prone skin. “LHA is less irritating than salicylic acid and has an extra affinity for pores so that you can get an even better unclogging effect,�� says Dr. Lewis. Peer-reviewed research has confirmed this, and the same review shows that LHA has also been shown to induce dermal thickening comparable to a retinoid and stimulate collagen and elastin production. What to look for: The research shows AHAs are effective OTC in 5 to 10 percent concentrations, while the BHA salicylic can range from 0.5 percent to 2 percent. LHA is used in 0.4 to 1 percent concentrations. You can find them in cleansers, exfoliants, serums, and moisturizers. We've got one of each for you here.The Runners UpYou may be reading this list and wondering why some buzzy ingredients didn’t make the cut. According to our experts, some ingredients have solid research behind them, but they’re tricky to formulate with, even trickier to get into the skin, or overhyped. These include:Vitamin C: Many dermatologists put vitamin C on their list of ingredients with solid research, and it does have a significant body of evidence proving its antioxidant powers, skin-brightening abilities, and crucial role in collagen production. Some cosmetic chemists—the ones who actually formulate the products you use on your skin every day—have a different take, pointing out the challenges of developing effective products with such a highly unstable ingredient. “You can show in a lab that vitamin C works great because they’re making it fresh, but when you go to a store and pick up a product that’s been on the shelf for six months, you’re most likely not getting the same effect,�� says Romanowski. “It breaks down or oxidizes while sitting on the shelf and then it’s useless.�� It’s also highly temperamental once you open the bottle. Vitamin C oxidizes when exposed to air, light, and heat. Encapsulating L-ascorbic acid (the most active form of vitamin C) and storing it in a dark or tinted bottle with an airless delivery system is your best bet for keeping your vitamin C stable.Peptides: It seems like they’re in everything, from nighttime moisturizers to lip plumpers, and these short chains of amino acids act as messengers, telling skin cells to pump out more collagen. They can also inhibit enzymes that break down collagen. The issue is that not all peptides can get into the skin—and there's virtually no way the average consumer would be able to suss that out on their own. “It depends on the vehicle, formulation, and the storage of the products,�� says Dr. Lee. She says, “A lot of the studies on peptides take place in an in vitro-controlled lab environment, not real-world settings, so I'm hesitant to recommend them unless they’re paired with a tried-and-true ingredient.�� Romanowski agrees that peptides are overhyped, but says real potential exists. “I think peptides are the most promising of things, and we might be able to get some real innovation from them, but we’re not there yet,�� he says.Hyaluronic acid: This humectant, also known as HA, is everywhere. It attracts water from the environment and the deeper layers of skin, helping that surface layer retain moisture and look more plump and supple. And studies do support these claims. “But it’s not any better than glycerin, another humectant,�� says Romanowski. “HA is produced in the body, so it has a nice story behind it, but the molecule is too large to penetrate into the skin, so you’re getting topical moisturization at best,�� he says. Why have these ingredients been touted as tried-and-true actives when they often can’t get into the skin or degrade before they even hit the skin? “As with many things in our industry, marketing usually gets in the way of what the science can show,�� says Romanowski. “Your skin is pretty good at blocking stuff out, and that’s the challenge with any active ingredient,�� he says. “That’s why things like retinol and salicylic acid work—they break down the glue that keeps skin together.”So, next time you’re tempted by an innovative new breakthrough ingredient that promises to smooth all your lines and wrinkles, remember it may work in a petri dish, but that doesn't mean it will on your skin. If you want no-nonsense skincare that does deliver, look for this very short list of research-backed, expert-approved ingredients.