Evidence-based reference

Ingredient Explainer

Plain English breakdowns of skincare actives. Not what to buy — what the research actually says, what concentrations are evidence-based, and what brands commonly overstate. Every claim is cited.

How to read the evidence badges: Human clinical trials carry the most weight for skincare claims. Animal and in-vitro studies can show a mechanism exists — they cannot confirm it works the same way in living human skin. We always tell you which type of evidence a claim rests on.

Allantoin

A naturally occurring compound (found in comfrey root and produced endogenously in most organisms) with documented keratolytic, wound-healing, and soothing properties. It promotes skin cell proliferation and accelerates healing of minor irritations and abrasions — used in clinical wound care formulations.

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Alpha Arbutin

A glycoside of hydroquinone that hydrolyses slowly in skin tissue to release hydroquinone — the most clinically proven skin-lightening compound — at lower concentrations and with less irritation than direct hydroquinone application. Inhibits tyrosinase, the enzyme controlling melanin synthesis.

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Azelaic Acid

Azelaic acid is an underrated multitasker: it calms inflammation, has some antibacterial action, and gently fades post-acne dark marks. It is a go-to for rosacea and for acne in people who also struggle with hyperpigmentation, and it is generally well tolerated — including in pregnancy (confirm with your doctor).

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Bakuchiol

A meroterpene phenol extracted from Psoralea corylifolia seeds that activates retinoid receptor pathways despite being structurally unrelated to retinol. One well-cited double-blind RCT (Dhaliwal et al.

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Strong evidence

Benzoyl Peroxide

Benzoyl peroxide is one of the most effective OTC treatments for inflammatory acne (the red, pus-filled kind). It kills acne-driving bacteria and, importantly, bacteria don’t become resistant to it the way they do to antibiotics.

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Centella Asiatica

An herbaceous plant used in traditional Ayurvedic and TCM medicine that has accumulated a meaningful modern evidence base. Active compounds — asiaticoside, asiatic acid, madecassic acid, and madecassoside — stimulate fibroblast proliferation and collagen synthesis, and accelerate wound healing.

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Ceramides

Ceramides are the lipids (fats) that make up much of your skin’s outer barrier — the "mortar" between skin-cell "bricks. " Topical ceramides help replenish that barrier, reduce water loss, and soothe dry, sensitive, or compromised skin.

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Strong evidence

Colloidal Oatmeal

Finely milled Avena sativa (oat) that has been FDA-approved as a skin protectant since 2003 — one of the few cosmetic ingredients with an OTC drug monograph for eczema and dry, itchy skin. Active components include avenanthramides (potent anti-inflammatory polyphenols unique to oats), beta-glucans (which form a soothing film and have immunomodulatory properties), and lipids that support barrier repair.

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Ferulic Acid

A hydroxycinnamic acid found in plant cell walls that is a potent antioxidant in its own right and uniquely effective at stabilising and potentiating other antioxidants. When combined with 15% L-ascorbic acid and 1% tocopherol (vitamin E), ferulic acid at 0.

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Glycolic Acid

The smallest alpha-hydroxy acid (AHA) and the one with the deepest penetration. Dissolves the chemical bonds holding dead corneocytes together, accelerating surface cell turnover.

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Hyaluronic Acid

Hyaluronic acid is a humectant — it binds water and holds it at the skin surface, giving an immediate plumper, more hydrated look. That hydration is real but temporary, and topical HA is not the same thing as the injectable fillers that share the name.

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Kojic Acid

A fungal metabolite (produced by Aspergillus and Penicillium species) that inhibits tyrosinase — the rate-limiting enzyme in melanin synthesis. Human clinical trials confirm it reduces hyperpigmentation, melasma, and post-inflammatory darkening; comparable to 4% hydroquinone in some head-to-head studies.

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Lactic Acid

An alpha-hydroxy acid (AHA) derived from fermented sugars with a larger molecular size than glycolic acid, resulting in more superficial penetration and better tolerance on sensitive skin. Beyond exfoliation, it has a secondary humectant effect — it is a component of the skin's natural moisturising factors (NMF).

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Licorice Root Extract

An extract from Glycyrrhiza glabra containing multiple bioactive compounds, of which glabridin is the most studied for skin brightening. Glabridin inhibits tyrosinase and UVB-induced pigmentation, while glycyrrhizin has anti-inflammatory properties.

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Mandelic Acid

An alpha-hydroxy acid (AHA) derived from bitter almonds with a larger molecular structure than glycolic acid, resulting in slower and more superficial penetration. This makes it better tolerated on sensitive or reactive skin and significantly less likely to cause post-inflammatory hyperpigmentation — making it the preferred AHA for medium-to-deep skin tones where glycolic acid can trigger PIH rather than fade it.

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Niacinamide

Niacinamide (vitamin B3) is one of the few "do-a-bit-of-everything" actives with real human evidence behind several of its claims. It strengthens the skin barrier, calms inflammation, and modestly fades dark spots.

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Panthenol (Vitamin B5)

A provitamin of pantothenic acid (B5) that penetrates the skin and converts to pantothenic acid, where it supports cellular metabolism, wound healing, and barrier repair. One of the most well-tolerated skincare ingredients across all skin types, including reactive and compromised skin.

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Peptides

Short chains of amino acids used in skincare with several proposed mechanisms: signal peptides (e. g.

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Polyglutamic Acid

A naturally occurring biopolymer produced by Bacillus subtilis fermentation that can hold 4–5 times more water than hyaluronic acid by weight. Unlike most molecular weights of hyaluronic acid, it primarily forms a film on the skin surface, preventing moisture evaporation rather than penetrating to deliver hydration from within.

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Resveratrol

A polyphenol antioxidant found in red grape skin, berries, and Japanese knotweed. It neutralises free radicals, has anti-inflammatory properties, and in vitro data suggests it activates sirtuin pathways involved in cellular repair.

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Retinaldehyde

A vitamin A aldehyde that sits one metabolic step closer to retinoic acid than retinol, making it more potent at lower concentrations while remaining available without a prescription. Converts to retinoic acid in the skin more efficiently than retinol, producing comparable anti-aging and anti-acne effects with less irritation than prescription tretinoin.

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Strong evidence

Retinol

Retinol is an over-the-counter member of the retinoid family — the single best-evidenced category for visible skin aging. It speeds up skin-cell turnover and stimulates collagen.

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Salicylic Acid (BHA)

Salicylic acid is an oil-soluble exfoliant (a beta hydroxy acid) that can get into pores and clear out the debris that drives blackheads and whiteheads. It is a mainstay for oily, congestion-prone skin and mild acne.

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Squalane

A hydrogenated and stabilised form of squalene — a lipid naturally produced by human sebaceous glands that declines measurably with age. Squalane (not squalene) is stable for use in cosmetics and functions as a lightweight, non-greasy emollient that replenishes skin lipids and reduces transepidermal water loss without occluding pores.

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Tranexamic Acid

Originally a haemostatic pharmaceutical drug still used in surgery to control bleeding. Reached dermatology after clinicians noticed patients taking it orally for other conditions experienced unexpected skin brightening.

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Vitamin C (L-ascorbic acid)

Topical vitamin C is an antioxidant that can help brighten skin tone and support collagen, and it complements sunscreen. The catch is formulation: pure L-ascorbic acid is notoriously unstable and oxidizes (turning yellow-brown) once exposed to air and light.

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Strong evidence

Zinc (Topical)

Zinc in skincare primarily appears as zinc oxide (in sunscreen) or zinc acetate/pyrithione/gluconate (in acne and anti-dandruff products). As an acne treatment, zinc reduces sebum production, inhibits Cutibacterium acnes colonisation, and has direct anti-inflammatory activity.

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