Matching foundation for a living teaches you fast that skin tone is never one colour. Almost every face I work on has some unevenness, and knowing which kind you are looking at changes everything about how you treat it and how you cover it.
In Short
- Two pigments decide your natural colour: eumelanin protects, pheomelanin does not
- Up to 30 per cent of pregnancy melasma persists after delivery, sometimes for years
- Post-inflammatory marks last longest on deeper skin tones, which is the opposite of what most articles say
- Hydroquinone is banned in UK cosmetics: prescription only, and illegal creams still circulate
What skin pigmentation actually is
Your skin has a base colour that exists independently of any sun exposure, set by cells called melanocytes sitting at the bottom of the epidermis. They produce melanin in two forms, and the ratio between them, not the number of melanocytes, is what makes one person fair and another deep brown. We all carry roughly the same melanocyte count.
Eumelanin is the brown to black pigment that absorbs ultraviolet radiation and gives real, though never complete, photoprotection. Pheomelanin is the yellow to red pigment dominant in fair skin and in natural redheads, and it does not shield the skin from UV in any meaningful way. Once melanin is made it is passed to the surrounding keratinocytes, then carried upward as those cells renew, which is what tints the surface evenly.
Why the colour stops being even
Pigmentation problems fall into two camps: too much melanin in one place, or too little. Hyperpigmentation is by far the more common, and it rarely has a single cause. Ultraviolet exposure drives most of it, hormones drive a good chunk of the rest, and inflammation of any kind, including a spot you picked, drives the marks people most often mistake for scars.
| What you are looking at | Typical trigger | How it behaves |
|---|---|---|
| Sun lentigines (age spots) | Cumulative UV on face, neck, hands | Flat, round, permanent without treatment |
| Melasma | Pregnancy, hormonal contraception, UV | Symmetrical patches, often stubborn |
| Post-inflammatory hyperpigmentation | Acne, eczema, friction, waxing, burns | Fades over months, slowest on deeper tones |
| Phototoxic reactions | Citrus oils and some medicines plus sun | Streaky marks where the product ran |
| Hypopigmented patches | Vitiligo, past inflammation, fungal causes | Needs a diagnosis, not a brightening serum |
Two corrections worth making to the version of this you usually read. First, melasma does not reliably disappear once hormones settle: a 2024 review in Clinical, Cosmetic and Investigational Dermatology notes that up to 30 per cent of pregnancy-related cases persist after delivery, sometimes for a decade, and that it commonly returns in later pregnancies. Second, lighter skin is not the tone that suffers most from pigmentation overall. Fair skin collects more sun lentigines with age, but post-inflammatory marks are deeper, darker and far slower to fade on Fitzpatrick types IV to VI.
The lightening products you should not buy
This is the part of the subject with real consequences. Hydroquinone is prohibited in cosmetics across the UK and EU, listed in Annex II of Regulation 1223/2009, and available in this country only on prescription through a route registered with the MHRA. It still turns up in unlabelled creams, and UK Trading Standards has run enforcement campaigns as recently as 2026 against illegal skin-lightening products sold through corner shops and food stores.
- Avoid anything listing hydroquinone, mercury or a strong steroid such as clobetasol or betamethasone.
- Treat missing or non-English ingredient labelling as a refusal, not a curiosity.
- Steroid misuse on the face thins skin permanently and can rebound the pigmentation worse than it started.
What does work is far duller: daily broad-spectrum sun protection at SPF 30 or above with a four or five star UVA rating, applied properly and reapplied, plus patience. UVA passes through cloud and window glass all year, which is why pigmentation creeps on during a British winter too.
Who studies this, and why it matters for products
Testing an active ingredient on pigmentation used to mean working with donated skin cells that varied from batch to batch. Phenocell, a preclinical contract research organisation based in Grasse, works instead with cells reprogrammed from induced pluripotent stem cells, the technique that won a Nobel Prize in 2012. It supplies melanocytes, keratinocytes and sebocytes of different phototypes in consistent quantities, for dermatology and ophthalmology research.
That phototype detail is the interesting bit for anyone who has ever wondered why a product works differently on their skin than on the model in the advert. If a brightening active is only ever tested on one cell type, its behaviour on the rest of us is guesswork.
The same technology is being pointed at acne
Pigmentation and acne overlap more than people expect, because the marks left behind after breakouts are pigmentation, not scarring. Acne itself is close to universal: the NHS puts it at around 95 per cent of people aged 11 to 30 affected to some extent, with 20 to 35 per cent developing moderate or severe forms, and about 3 per cent of adults still dealing with it past 35.
Phenocell’s sebocyte work targets exactly that mechanism, the oil-producing cells whose dysfunction starts the blocked pore. In-vitro models of those cells let researchers watch seborrhoea behave without recruiting a single volunteer, which is how most cosmetic actives are screened before they ever reach a face.
If you want the beauty-counter side of all this, how brightening actives are sold and what the claims are allowed to say, I have written about skin pigmentation from the beauty industry’s angle separately.
Updated 11 August 2026. General health information, not medical advice. Any new, changing or irregular pigmented patch should be seen by a GP or dermatologist rather than treated at home.
Sources: NHS guidance on acne and on sunscreen use; Prevention of Melasma During Pregnancy, Clinical, Cosmetic and Investigational Dermatology, 2024; Regulation (EC) 1223/2009, Annex II, on hydroquinone; UK Trading Standards campaigns on illegal skin-lightening products, 2026; Phenocell company information on iPSC-derived skin cells.
What does your skin do in the sun?
Spots, freckles, patches that come and go: tell me what yours does and how you deal with it. I read every comment and it shapes what I write next.