The Big Skincare Myths — Debunked by Science

The Science

The skin is a barrier organ — its primary biological function is to prevent external substances from entering the body, not to facilitate their entry. Transdermal absorption of molecules is tightly controlled by the stratum corneum, the outermost skin layer composed of corneocytes embedded in a lipid matrix. This structure is extraordinarily effective at blocking most molecules.

For a molecule to penetrate skin meaningfully, it generally needs: a molecular weight below 500 Daltons, appropriate lipophilicity (log P value 1–4), and sufficient concentration to drive a diffusion gradient. Most environmental "toxins" are either too large, too hydrophilic, or present in insufficient concentration to cross the intact stratum corneum. This is why pharmaceutical transdermal drug delivery (e.g., nicotine patches) requires extremely careful molecular engineering — most molecules simply don't penetrate.

As for "detoxing" — the liver and kidneys are your detoxification organs. No topical skincare product can remove substances from inside your body. Activated charcoal masks remove surface debris (sebum, dead skin cells) from the follicle opening — a cosmetic effect, not a systemic detox.

The Science

Skin does not develop pharmacological tolerance to cosmetic actives the way opioid receptors downregulate in response to opioids. Skin cells renew on a 28–50 day cycle (slowing with age). Retinol, for instance, continues upregulating collagen-related genes in fibroblasts across multi-year use — there is no mechanism by which fibroblasts "learn" to ignore retinoid signalling.

What does happen: initial visible results can plateau as the most responsive skin improvements are made in the early months. But this plateau represents maintained improvement, not lost efficacy. A retinol user may stop seeing new wrinkle reduction after 12 months because existing wrinkles are already optimised — but stopping retinol would cause regression. The product is still working; the visible endpoint has been approached.

One genuine exception: skin can adapt its sebum production in response to over-stripping cleansers, producing more oil to compensate for excessive dryness. This is physiological adaptation, not product tolerance — and the solution is to use gentler cleansers, not to rotate aggressively.

The Science

Skin hydration is primarily determined by the stratum corneum's water-binding capacity (natural moisturising factors — NMFs, including urocanic acid, amino acids, and PCA derivatives) and transepidermal water loss (TEWL) rate, which is controlled by the lipid lamellae in the stratum corneum. Systemic hydration has a minimal and indirect effect on these parameters.

A 2015 systematic review in Skin Research and Technology examined multiple studies on water intake and skin hydration. The conclusion: in normally hydrated individuals, increasing water intake did not produce measurable improvement in skin hydration parameters. Only subjects who were clinically dehydrated (below normal total body water) saw skin hydration respond to increased intake.

What actually hydrates skin: humectants (hyaluronic acid, glycerin, sodium PCA) that draw water into the stratum corneum, and occlusives (ceramides, shea butter, petrolatum) that reduce TEWL. These are topical solutions to a topical problem. Drinking water supports overall health — just don't expect visible skin hydration benefits unless you're clinically dehydrated.

The Science

This is demonstrably false and arguably the most damaging myth in clean beauty. The European Dermatology Forum's contact allergy data consistently shows that botanical ingredients — particularly essential oils, plant extracts, and botanical fragrances — are among the most common causes of allergic contact dermatitis in cosmetic products.

Limonene (citrus, cannabis), linalool (lavender, coriander), geraniol (rose, geranium), cinnamal (cinnamon, cassia), isoeugenol (carnation, ylang ylang) — all natural, all major EU-listed allergens requiring declaration above threshold concentrations. Poison ivy is natural. Urushiol — the contact allergen responsible for poison ivy rash — is entirely plant-derived.

Conversely, synthetic niacinamide, synthetic ceramides (identical to human skin ceramides), and synthetically-produced hyaluronic acid have extremely low sensitisation rates in the global population — lower than most botanical alternatives. The origin of a molecule does not determine its skin compatibility.

The Science

There is no systematic evidence that price correlates with cosmetic efficacy. A 2021 analysis in the Journal of Cosmetic Dermatology examined moisturiser formulations across multiple price points and found no meaningful correlation between price and measured barrier repair efficacy.

Pricing in skincare is determined by: marketing spend (often the largest cost element), packaging (a 50ml glass bottle with gold cap costs many times more than a pump tube), brand positioning, retail margins (luxury department stores take 50%+ margins), ingredient exoticism (novelty premium), and celebrity endorsement. Actual ingredient costs are rarely the pricing driver — retinol, for instance, costs approximately €0.50–2 per 50ml formulation at 0.3% — regardless of whether the product retails at €15 or €120.

The counter-examples are numerous: The Ordinary's 0.3% Retinol in Squalane (€6) contains the same active at the same evidence-based concentration as several €80+ competitors. CeraVe at €10 contains three ceramide types and cholesterol at proven barrier-repairing concentrations. La Roche-Posay Cicaplast at €12 contains madecassoside at clinical-trial concentrations.

The Science

UVA radiation — the primary driver of photoageing and a significant contributor to skin cancer risk — penetrates cloud cover and glass with minimal attenuation. UVA accounts for 95% of UV radiation reaching the Earth's surface. While UVB is largely blocked by cloud cover and glass, UVA is not. Cloud cover reduces total UV by only 20–40% — not by the 90%+ reduction people intuitively assume.

Window glass: standard glass blocks UVB almost completely but transmits UVA effectively. If you work near a window, you are receiving meaningful UVA exposure even indoors. This has clinical significance — asymmetric photoageing on the driver's side of the face vs passenger's side is documented in multiple dermatology case studies.

UVA induces indirect DNA damage via reactive oxygen species, degrades collagen and elastin via matrix metalloprotease activation, and contributes to melanogenesis. These effects accumulate over years of daily exposure — including cloudy days, window exposure, and brief outdoor moments. Cumulative UV dose is what matters, not single high-intensity events.

The Science

Pores do not have muscles. They cannot actively open or close. The follicle opening (what we call a "pore") is a passive anatomical structure — a channel lined with keratinised epithelium leading to a sebaceous gland. There are no arrector pili muscles attached to follicles (those are attached to hair shafts for piloerection) and no smooth muscle capable of follicular dilation or constriction.

What heat does: steam and warm water increase local skin temperature, which slightly increases blood flow and can temporarily loosen the sebum plug within a follicle by reducing its viscosity. This gives a modest cleansing facilitation effect. Cold water constricts superficial blood vessels (vasoconstriction), which reduces redness and temporarily makes the skin surface look smoother. Neither is "opening" or "closing" the pore anatomically.

Pore size is determined by genetics, sebum production rate, and age-related loss of surrounding collagen support. The only interventions with meaningful evidence for reducing visible pore size: retinoids (increase collagen around follicles), niacinamide (reduces sebum production over time), and BHA exfoliants (clear intrafollicular debris, reducing the plugged appearance).

The Science

The periorbital skin (around the eyes) is thinner than facial skin elsewhere, has fewer sebaceous glands, and is more prone to showing volume loss, fine lines, and dark circles. These are genuine anatomical differences. The question is whether they justify a separate product category — and whether dedicated eye creams deliver meaningfully different formulations.

In most cases, the answer is no. The majority of eye creams contain the same actives as facial moisturisers — hyaluronic acid, peptides, caffeine, retinol equivalents, ceramides — in similar or identical concentrations. A 2021 review in Dermatology and Therapy found no clinical evidence that dedicated eye creams outperform a well-formulated facial moisturiser applied to the periorbital area for any of the claimed endpoints (dark circles, puffiness, fine lines).

Genuine reason to consider an eye cream: if your regular moisturiser contains high concentrations of actives (strong retinol, high AHA, intensive peels) that might cause irritation in the more sensitive eye area. In that case, a milder formula in the periorbital zone makes sense. But as a separate product category — the formulation science doesn't support it.

The Science

The term "oil" describes an enormous and chemically diverse category of ingredients. Comedogenicity — the ability of an ingredient to block follicles and contribute to comedone formation — varies dramatically across oils and is not inherent to the oil category.

Comedogenicity ratings (0–5 scale) from dermatology literature show wide variation: Squalane (0 — completely non-comedogenic), Jojoba oil (2 — low), Hemp seed oil (0–1), Rosehip oil (1), Argan oil (0), Marula oil (3–4), Coconut oil (4), Flaxseed oil (4), Wheat germ oil (5). Blanket avoidance of all oils because of acne concern ignores this variation entirely.

Moreover, skin's own sebum is already an oil — oil-based moisturisers don't add a foreign substance, they supplement or mimic the skin's own lipid layer. For dry or compromised barriers that overproduce sebum in response to dryness (the paradox of oily-dehydrated skin), appropriate oil application can actually reduce sebum production by signalling to sebaceous glands that barrier lipids are adequate.

The Science

This myth has a legitimate historical basis that no longer applies to modern cleansing products. Traditional alkaline soap bars (pH 9–10) genuinely disrupted the acid mantle significantly, and a pH-correcting toner after washing with such a product made scientific sense. The problem: few people use bar soap as their face cleanser anymore.

Modern syndets (synthetic detergent cleansers) — the gel cleansers, cream cleansers, and micellar waters that dominate the market — are formulated at pH 5–6, matching or close-matching skin's natural pH. Research by Schmid-Wendtner and Korting (2006) demonstrated that even after meaningful pH disruption, healthy skin restores its own surface pH to normal within 30–90 minutes via organic acid secretion. No external correction is needed.

The practical test: check your cleanser's pH. If it's a modern syndet at pH 5.5–6.5, you do not need a pH toner afterward. If you're using a true soap bar, swap the cleanser. Toners that contain actives (BHA, AHA, niacinamide, hyaluronic acid) serve a different and legitimate purpose — as an active delivery step — but "pH restoration" is not a valid justification in contemporary routines.