Corneotherapy: Respecting Physiology for All Skin Tones
Adapted from a lecture I gave at Tones of Beauty 2026
Choosing to work in the skin industry means accepting a considerable responsibility. Every day, people bring their faces, their vulnerabilities and their insecurities into our treatment rooms, and they trust us with the part of themselves they present to the world.
Because of that trust, I want to begin with a vision.
Imagine a client walking into any skin clinic, anywhere. The therapist across from them has confidence, understanding and no hesitation. Whatever the colour of that skin, the professional is fully equipped to work out what this skin, as a living organ, needs in that moment.
If we are honest, we have not yet realised that future as an industry.
Skin Health is Balance
For decades, the industry has been preoccupied with what we can see. We talk about glow, the erasure of lines and the lifting of pigment, and we have treated skin as an appendage to be corrected.
I would like us to consider skin as an ecosystem rather than an oil painting, and to make balance the goal rather than visual perfection.
True skin health is not the absence of a wrinkle or a perfectly uniform tone. The skin is constantly recalibrating itself to maintain homeostasis, and when we concentrate solely on aesthetics we often end up working against those natural mechanisms.
We see pigment and want to blast it away, or we see oil and want to strip it. Shifting our focus to function means we stop looking at symptoms and start looking at systems.
With functionality, we become more concerned with the machinery…
A function-led approach draws our attention to the following:
• The keratinocyte life cycle and how it shapes the formation of the barrier defence systems
• Transepidermal water loss (TEWL) and the regulation of water in the skin
• The acid mantle and the pH needed to give the skin microbiome a hospitable environment
• Inflammation, and keeping it from shifting from a helpful response to a chronic concern
• Cellular health, so melanocytes, keratinocytes & Langerhans cells can each fulfil their purpose efficiently
• Lipid balance, including the ratio of 3:1:1 of ceramides, cholesterol and free fatty acids
This list covers the epidermis only and everything itemised is universal.
Everyone reading this, and every client who walks through your door, relies on the same mechanisms.
When we achieve homeostasis we achieve skin health, and improved appearance follows as a by-product. The industry is moving steadily in this direction, with growing interest in skin longevity and regenerative techniques and the skin barrier has even become rather fashionable.
So, where does Corneotherapy fit in?
Corneotherapy has been taking this approach all along.
It emerged from corneobiology research in the 1960s, which showed that the Stratum Corneum remains metabolically active. I am aware that corneocytes are terminal cells that have lost their nucleus and organelles, but they still play an important role. Together with the multilamellar lipids and the acid mantle they form the barrier, which protects us and regulates TEWL.
Corneotherapy is both functional and holistic, and professionals across many disciplines and countries have embraced it. It seeks to optimise the epidermis and to prioritise the integrity of the barrier at all times. We do this by being considerate in the actions we take and the ingredients we use, so that every step works with the skin rather than against it.
Corneotherapists often compare the barrier to the roof of a house. If the roof is broken, the house leaks, the warmth escapes and rot begins to set in. Skin behaves in much the same way. A compromised barrier leaves it exposed to pathogens, allergens, pollutants and water loss, which in turn makes sensitivity, inflammation, dehydration and infection more likely. In simple terms, we want to keep the goodies in and the baddies out.
The skin builds its own roof, and when we understand its function rather than treating it as an appendage, clinical practice looks very different. This is what I call a skin health-first approach.
If skin health is homeostasis, then skin tone has no bearing on what health means. Homeostasis looks different for every individual, because each person has their own baseline, variables and point of balance.
Function may be universal, but there are distinct nuances between all skin tones that matter.
A knowledge gap remains across the industry, starting at the foundations of skin education, and if we want to be representative and safe for all clients we have to close it.
The Physiological Nuances
1. More eumelanin. Skin of colour contains more eumelanin, the genetically determined constitutive pigment. A study of cultured melanocytes from donors of different ethnic backgrounds found that eumelanin content increased progressively from lighter to darker skin (Wakamatsu et al., 2006). Eumelanin is highly efficient at absorbing UV radiation and neutralising free radicals.
2. Larger melanosomes, distributed individually. The way pigment is packaged matters as well as the amount. In lighter skin, melanosomes tend to be grouped together inside keratinocytes, whereas in darker skin they are larger and dispersed singly (Thong et al., 2003). This creates a more even canopy over the keratinocyte nuclei and helps absorb UV before it can cause DNA damage (Kaidbey et al., 1979). When we think about UV protection, then, distribution is as relevant as quantity.
3. Slower visible ageing. Some research points to differences in collagen, elastin and fibroblast activity. Rawlings (2006) argues that the greatest contributor is melanin itself, since it reduces cumulative UV damage across a lifetime and therefore reduces photo-ageing.
4. A lower surface pH. A study comparing skin from three populations found that darker skin had a surface pH roughly 0.5 units more acidic than lighter skin. The researchers went further than observation and showed that the lower pH improved lipid processing, strengthened the barrier and sped up barrier recovery (Gunathilake et al., 2009). It is a useful reminder of how much small pH changes can affect barrier performance.
5. Broad-spectrum protection that does not prevent burning. Roughly five times more UV radiation reaches the upper dermis in Caucasian skin than in Black skin. The researchers likened melanin to a neutral density filter, which reduces all wavelengths fairly evenly (Kaidbey et al., 1979). Broad-spectrum is not the same as complete, however. Every skin tone can burn, accumulate DNA damage and develop skin cancer, so we should never assume that darker skin does not need photoprotection.
6. Differences in vitamin D synthesis. The melanin that protects darker skin from UV also reduces the UVB penetration needed to synthesise vitamin D. A large international study of African-origin populations found that vitamin D levels fell with increasing distance from the equator (Durazo-Arvizu et al., 2014). In northern Europe, where winter UVB is already limited, darker skin may need considerably longer exposure to produce the same amount (Lowe and Bhojani, 2017). Vitamin D status is not something we diagnose, but this physiology helps explain why deficiency can be more prevalent in some populations, and it is a relevant consideration when we think about wound healing, barrier strength and inflammatory skin conditions.
7. Larger mast cell granules. Several studies report larger granules in the mast cells of darker skin (Rawlings, 2006; McColl et al., 2020). Because these granules store histamine and other inflammatory mediators, they may allow a greater capacity for inflammatory release. This supports the case for minimising unnecessary irritation or trauma during treatment.
8. Larger melanocytes with longer dendrites. Many people are surprised to learn that melanocyte numbers do not differ between skin tones. One of the earliest comparative studies found instead that the melanocytes in darker skin are larger, with longer and more highly branched dendritic arms (Hu and Lesney, 1960). This allows pigment to be passed to more surrounding keratinocytes, and it helps explain why inflammation can produce extensive and persistent post-inflammatory hyperpigmentation (PIH).
9. A more compact stratum corneum, with possibly lower ceramides. The evidence here is not entirely consistent. Some studies suggest that darker skin has a more compact stratum corneum with stronger corneocyte cohesion, and some report lower ceramide levels. Others have found ceramide levels in Asian skin similar to those in Caucasian skin, despite a different response to barrier disruption (Rawlings, 2006; Gunathilake et al., 2009). The lesson is that ceramides alone do not determine barrier function. The organisation and structure of the stratum corneum matter more, so barrier assessment should always be holistic.
The Risks
More pigment brings more risk. Darker skin tones are more vulnerable to PIH and to scarring, including keloid and hypertrophic scars, when treatments push the skin too hard. Melanocytes in darker skin respond strongly to stress, whether from inflammation, heat or physical pressure, and they increase pigment production quickly, which is what drives PIH.
Healing is affected too. Overstimulated melanocytes can disrupt fibroblasts, the cells responsible for repair, which may lead to excess collagen production and scarring that extends beyond the original wound. In short, the melanocyte pathway in darker skin is highly reactive and tends to push back when pushed too hard.
For a corneotherapist, very little changes, because we were never working with physical, thermal or chemical stress in the first place. For professionals using correction-led or aggressive protocols, understanding the skin in front of them is essential, and the question to ask is what justifies the approach.
The Fitzpatrick Failure
The industry relies heavily on the Fitzpatrick scale to navigate these risks, yet it was developed in 1975 to predict how a person’s skin would respond to UV radiation in medical treatment. It was never intended as a comprehensive measure of reactivity or ethnicity. A 1997 study found that objectively measured skin pigmentation predicted minimal erythema dose more accurately than the subjective Fitzpatrick classification (Damian et al., 1997).
This is not a reason to abandon the scale. It does show that we need to stop reading charts in isolation and consider the individual as a whole, which depends on a strong consultation process. A consultation should not be a box-ticking exercise or a contraindication check to satisfy insurers. It is our best opportunity to learn about the life the skin leads.
Skin is a living ledger that records every chapter of a person’s life. It reflects their environment, their lineage, their daily stress and their habits, and our task is to ask the right questions and interpret what we find. Understanding the life the skin leads helps us see why it reacts as it does and lets us look beyond symptoms, which sits at the heart of corneotherapy.
The Fear Factor
When I talk to professionals about this shift, I often meet a deep-seated fear that comes from a lack of foundational knowledge and hands-on experience with a wide range of skin tones. Many therapists are afraid of causing damage. There is a social fear too, of getting the language wrong, saying something politically incorrect or offending a client without meaning to.
I see this as a sign of genuine care and respect for clients, but it should not become a reason to avoid these conversations. It can be a prompt to learn instead. Terminology keeps evolving and it is hard to keep up, yet if we take the time to learn and to attend to the individual in front of us, clients will feel respected and heard.
If you are unsure how a particular skin structure behaves, be humble enough to ask. You might say, “I want to make sure I respect your skin’s unique physiology. Can you tell me a little about how your skin typically behaves when it meets X, Y or Z?” Approaching a consultation with real curiosity about the life the skin leads tends to replace fear with connection and trust.
The Future we Build
The professional skin industry is at a turning point, and events like Tones of Beauty are evidence of the need to support all skin tones. The future lies in understanding systems, respecting barriers and honouring each person’s path to homeostasis, which is the very essence of corneotherapy.
I would like us to build an industry where no client feels like an anomaly or an afterthought in a textbook, and where education equips every therapist to work with the diversity of human physiology with skill and care.
Any skin tone, walking into any clinic and be properly understood and properly respected.
That is the future I would like to see.
Maria Rylott-Byrd
The Corneotherapy Consultant™
Education, Mentoring, Events, Consultancy, Advocacy
BA Hons I CIDESCO I CIBTAC I AET
Chair, International Association for Applied Corneotherapy
References
Damian DL, Halliday GM and Barnetson RSC (1997) ‘Prediction of minimal erythema dose with a reflectance melanin meter’, British Journal of Dermatology, 136(5), pp. 714–718.
Durazo-Arvizu RA, Camacho P, Bovet P et al. (2014) ‘25-Hydroxyvitamin D in African-origin populations at varying latitudes challenges the construct of a physiologic norm’, American Journal of Clinical Nutrition. https://doi.org/10.3945/ajcn.113.066605
Gunathilake R, Schurer NY, Shoo BA et al. (2009) ‘pH-regulated mechanisms account for pigment-type differences in epidermal barrier function’, Journal of Investigative Dermatology. https://doi.org/10.1038/jid.2008.442
Hu F and Lesney PF (1960) ‘Comparative studies of human melanocytes in skins of varying degree of pigmentation’, Henry Ford Hospital Medical Journal, 8(1), pp. 50–54. https://scholarlycommons.henryford.com/hfhmedjournal/vol8/iss1/11
Kaidbey KH, Agin PP, Sayre RM and Kligman AM (1979) ‘Photoprotection by melanin: a comparison of black and Caucasian skin’, Journal of the American Academy of Dermatology. https://doi.org/10.1016/s0190-9622(79)70018-1
Lowe NM and Bhojani I (2017) ‘Special considerations for vitamin D in the south Asian population in the UK’, Therapeutic Advances in Musculoskeletal Disease. https://doi.org/10.1177/1759720X17704430
McColl M, Boozalis E, Aguh C, Eseonu AC, Okoye GA and Kwatra SG (2020) ‘Pruritus in Black skin: unique molecular characteristics and clinical features’, Journal of the National Medical Association. https://doi.org/10.1016/j.jnma.2020.07.002
Rawlings AV (2006) ‘Ethnic skin types: are there differences in skin structure and function?’, International Journal of Cosmetic Science. https://doi.org/10.1111/j.1467-2494.2006.00302.x
Thong H-Y, Jee S-H, Sun C-C and Boissy RE (2003) ‘The patterns of melanosome distribution in keratinocytes of human skin as one determining factor of skin colour’, British Journal of Dermatology, 149(3), pp. 498–505. https://doi.org/10.1046/j.1365-2133.2003.05473.x
Wakamatsu K, Kavanagh R, Kadekaro AL et al. (2006) ‘Diversity of pigmentation in cultured human melanocytes is due to differences in the type as well as quantity of melanin’, Pigment Cell Research. https://doi.org/10.1111/j.1600-0749.2006.00293.x
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