Skincare ingredients

Azelaic acid is a dicarboxylic acid originally derived from grains, available as prescription 15 to 20% formulations and OTC around 10%. It is one of the quiet overachievers in dermatology: a 2020 Cochrane review rated its acne evidence moderate quality (better than salicylic acid or niacinamide), a 2024 network meta-analysis found 20% azelaic acid had the largest effect among topicals for papulopustular rosacea, and meta-analysis suggests it can match or beat hydroquinone for melasma. It is also one of the few actives considered safe in pregnancy.

3 graded uses

Bakuchiol is a plant-derived compound marketed as natural retinol, and it has more legitimate data than most botanical trends: it activates retinoid-like gene expression without being a retinoid, and a randomized, double-blind, head-to-head trial found it matched 0.5% retinol on wrinkles and pigment with less irritation. That said, the entire clinical literature is a handful of small studies. A 2024 review of 15 human trials found 12 were unblinded and uncontrolled, so comparable-to-retinol currently rests mainly on one 44-person, 12-week study.

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Glycolic acid is the smallest and most used alpha hydroxy acid, sold in leave-on products around 5 to 10% and used in professional peels at 20 to 70%. Randomized trial evidence supports professional peels for acne and shows that even low-strength daily creams modestly improve sun-damaged skin. The honest picture: peels have decent trial support, while the dramatic resurfacing claims made for low-percentage home products rest on evidence showing modest, gradual change.

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Hyaluronic acid is a sugar molecule that holds many times its weight in water and is a natural component of skin. As a topical humectant it reliably boosts surface hydration, which temporarily plumps skin and softens the look of fine lines. The published efficacy studies are small, short, and mostly manufacturer-sponsored, and the popular idea that a serum can restore the deep HA your skin loses with age is not supported: topical HA sits in and near the surface layers. Hydrator, yes; filler in a bottle, no.

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Hydroquinone is the reference-standard skin lightener, used for melasma and stubborn dark patches for over 50 years. Meta-analyses of randomized trials consistently rank hydroquinone alone, and especially triple combination cream (hydroquinone plus tretinoin plus a corticosteroid), as the most effective self-applied melasma treatments. It moved to prescription-only status in the US in 2020, reflecting real but manageable risks: irritation, rebound pigmentation, and rare ochronosis (a paradoxical blue-black darkening) with prolonged unsupervised use.

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Niacinamide is a form of vitamin B3 that shows up in everything from cleansers to serums, largely because it is cheap, stable, and almost never irritates. It has real randomized trial support for pigment problems, where 4% performed comparably to 4% hydroquinone in a split-face trial, and split-face data for aging signs. For acne and for the reduces-pores claim, the evidence is much thinner than the marketing suggests: a 2020 Cochrane review judged the acne evidence low quality.

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Retinol is the over-the-counter cousin of tretinoin and the default anti-aging ingredient in cosmetics. The skin must convert it to retinoic acid in two steps, so it is weaker and gentler than tretinoin. Head-to-head trials suggest well-formulated retinol can approach tretinoin's results on photoaging, but a 2021 systematic review of OTC retinol products found most vehicle-controlled trials were small, short, or industry-run, and several found no significant difference from vehicle. The gap between marketing claims and trial quality is real, even though the biology is sound.

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Salicylic acid is the standard OTC acne acid, an oil-soluble exfoliant that gets into pores in a way water-soluble acids cannot. It has been used medicinally for a very long time and is FDA-monographed for acne at 0.5 to 2%. The surprise for most consumers: a 2020 Cochrane review found the trial evidence behind topical salicylic acid for acne is of low certainty, with high risk of bias, even though clinical experience and peel studies are broadly supportive. It works, but the trial literature is weaker than its reputation.

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Tranexamic acid is a repurposed anti-bleeding drug that turned out to quiet the signaling between blood vessels, UV-stressed skin cells, and pigment cells that drives melasma. Oral TXA has the strongest data; topical 2 to 5% versions now appear in serums and have randomized trial support showing meaningful pigment reduction, in several comparisons performing near hydroquinone with less irritation. It is one of the more promising newer pigment ingredients, though topical trials remain small and mostly short.

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Tretinoin is prescription-strength vitamin A acid and the most studied topical anti-aging and acne drug in dermatology, with FDA approval for both uses. It has decades of randomized controlled trials behind it, including recent meta-analyses pooling over 1,300 patients for photoaging alone. It is the benchmark that other retinoids, including over-the-counter retinol, are measured against. The main tradeoffs are irritation in the first 4 to 8 weeks and the need for a prescription in most countries.

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Topical vitamin C is the standard antioxidant serum ingredient, used for brightening, sun-damage repair, and pigment. A 2023 systematic review of randomized controlled trials found it genuinely improves photoaged skin and helps melasma, though effects are gradual and generally smaller than prescription options. Its biggest practical problem is chemistry: L-ascorbic acid is unstable and penetrates skin poorly unless formulated at low pH, so many products on shelves have likely lost potency before they reach your face.

3 graded uses