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Skin Condition · Kensington, London
Dark, Thickened, Velvety Skin: Acanthosis Nigricans Explained
Acanthosis nigricans is a skin change that produces dark, thickened, velvety patches in the body folds, most often the neck, armpits and groin. The skin can look ingrained with dirt but does not wash clean. It is usually a sign of something happening elsewhere in the body rather than a disease of the skin itself.
- Cause investigated, not covered
- Experience across skin tones
- Kensington clinic
- Medically reviewed by Dr Prasad
This page reflects how acanthosis nigricans is assessed and managed at Faciem, and is reviewed for clinical accuracy.
Last reviewed: 15 September 2026.
Patient information only. Dark, velvety thickening in the skin folds can point to an underlying medical cause, so assessment matters as much as treating the appearance. Any plan follows a face-to-face consultation with Dr Prasad.
Patients since 2019
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TL;DR
Acanthosis nigricans is dark, thickened, velvety skin that develops in the body folds, typically the neck, armpits and groin. It is frequently associated with insulin resistance, and is also seen alongside excess weight, certain hormonal conditions and occasionally particular medicines. The appearance can usually be improved with topical treatment, but the more important step is establishing why it has appeared. Assessment at Faciem is by Dr Prasad, a GMC-registered doctor.
- Velvety dark patches in the skin folds
- Often a sign of insulin resistance
- Investigate the cause, not only the skin
About the Condition
What Is Acanthosis Nigricans?
Acanthosis nigricans is a thickening and darkening of the skin that develops symmetrically in flexural areas — the sides and back of the neck, the armpits, the groin and under the breasts. The affected skin takes on a velvety, slightly raised texture, and the colour ranges from light brown to almost black.
What acanthosis nigricans looks and feels like
The patches are usually symmetrical and build slowly, so people often notice them only once the contrast against surrounding skin becomes obvious. Texture is the giveaway: the skin feels velvety or faintly furred rather than scaly, and the normal skin lines deepen into ridges you can feel with a fingertip. Colour ranges from light brown through grey-brown to almost black. The back and sides of the neck are the most common site, followed by the armpits, the groin, under the breasts and the creases of the knuckles and elbows. Small skin tags frequently appear in the same areas. The patches are not usually itchy or sore, though skin inside a fold can chafe. A common experience is scrubbing at the area in the belief that it is ingrained dirt, which irritates the skin and tends to darken it further.
Who tends to develop it
Acanthosis nigricans occurs at any age, including in children and teenagers, and is recognised more often in people with brown and black skin. Skin tone is recorded on the Fitzpatrick scale at the first assessment, because it changes how the condition is treated as well as how often it is seen: acanthosis nigricans is most frequently diagnosed in Fitzpatrick IV to VI skin, and in those tones the risk being managed during treatment is post-inflammatory pigmentation. Strong exfoliating acids, aggressive in-clinic exfoliation or an over-concentrated lightening agent can leave a darker mark than the patch they were meant to clear, so concentrations are built up gradually and a small test area is used first. Its strongest association is with insulin resistance, so it is seen more commonly in people carrying excess weight, though it also appears in people of average weight. Polycystic ovary syndrome, an underactive thyroid and other hormonal conditions are recognised associations. A small number of people have a familial form that appears in childhood with no metabolic cause behind it. Certain medicines are occasionally responsible. Rarely, and particularly where the change comes on quickly and extensively in an adult, it can accompany an internal illness. Clinically, what matters is less who develops it than how fast it appeared and what else has changed.
What it is often confused with
The most frequent misreading is ingrained dirt or poor washing, which causes real distress and leads to scrubbing that thickens and darkens the skin further. Post-inflammatory hyperpigmentation following friction, shaving or a rash can look similar, but it traces the shape of the earlier irritation and lacks the velvety thickening. Terra firma-forme dermatosis looks almost identical yet wipes away with alcohol, which is a simple bedside test. Confluent and reticulate papillomatosis produces a comparable brown change on the trunk with a net-like edge. Erythrasma, a superficial bacterial infection of the folds, is flatter, browner and often slightly scaly. Darkening under the arms after years of shaving or deodorant use is friction and irritation, not acanthosis nigricans. The distinguishing feature in each case is the velvety, thickened texture, which is felt more reliably than it is seen.
Causes & Contributing Factors
What Causes Acanthosis Nigricans?
Acanthosis nigricans is caused by skin cells and pigment-producing cells being stimulated to multiply, most often by high circulating insulin. That is why it is regarded as a visible marker of what is happening internally rather than a disease of the skin. Hormones, some medicines and, rarely, internal illness can produce the same effect.
Insulin resistance
Where the body responds poorly to insulin, levels in the blood rise and insulin can act on receptors in the skin that drive cells to multiply. This is the most common explanation, and it may be present long before blood sugar itself becomes abnormal.
Excess weight
Acanthosis nigricans is more common in people carrying excess weight, partly through the link with insulin resistance and partly because friction between skin surfaces adds to the thickening. Weight change often improves the appearance, though rarely on its own.
Hormonal conditions
Polycystic ovary syndrome, an underactive thyroid, Cushing’s syndrome and acromegaly are all recognised associations. These conditions usually produce other signs as well, which is one reason a general medical assessment matters more than treating the skin alone.
Certain medicines
Nicotinic acid, some oral contraceptives, systemic corticosteroids and certain hormone treatments have been linked with acanthosis nigricans. Where a medicine is responsible the skin often settles after it is reviewed — always with the doctor who prescribed it, never by stopping it yourself.
Family tendency and friction
A small number of people have an inherited form that appears in childhood or adolescence with no metabolic cause. Separately, repeated rubbing from clothing, jewellery or shaving can thicken and darken skin in the same areas and add to the appearance.
Treatments We Offer
How Acanthosis Nigricans Is Treated at Faciem
Treatment for acanthosis nigricans works on two fronts: improving the appearance of the skin itself, and identifying what is driving the change. Both are handled at Faciem Dermatology & Medical Clinic on Kensington Church St, London, where assessment is led by Dr Prasad. Topical treatment can lighten and smooth the affected folds considerably, and the improvement tends to hold better once the underlying cause is being managed.
01
Medical-Grade Skincare
Active topical ingredients, including the ZO Skin Health range used at the clinic, exfoliate the thickened surface and reduce the excess pigment in the affected folds. For acanthosis nigricans this is usually the mainstay of treatment, and the regime is chosen for the skin tone being treated to reduce the risk of further darkening.
Best for: lightening and smoothing the affected folds
Read about Medical-Grade Skincare
02
Hydrafacial
Hydrafacial removes the build-up of dead skin cells that contributes to the rough, thickened surface, and helps topical products applied afterwards work more effectively. It is used alongside a skincare regime, not in place of one.
Best for: exfoliating thickened, built-up skin
Read about Hydrafacial
03
Dermatology Consultation
Acanthosis nigricans is often the first visible sign of a metabolic or hormonal problem, so assessment matters as much as treatment. A consultation establishes what is driving the change, arranges blood tests where they are indicated, and considers prescription topical treatment.
Best for: finding the underlying cause
Read about Dermatology Consultation
Prescription topical treatments, including agents that reduce pigment, may be considered following assessment where they are appropriate. Suitability, sequence and timing are decided at a face-to-face consultation with Dr Prasad, and results vary between individuals.
When to Seek Medical Advice
When Should You See a Doctor About Dark, Velvety Skin?
Dark, velvety thickening in the skin folds deserves a medical assessment, not only cosmetic treatment, because it is often a visible marker of something happening internally. Change that has come on quickly or spread widely in an adult is the most important reason to be seen, and simple blood tests settle a great deal.
Worth getting checked
- Dark, velvety patches appearing in the neck, armpits or groin for the first time
- Skin changes that have developed quickly or are spreading, particularly in adulthood
- Increased thirst, passing more urine, tiredness or unexplained weight change alongside the patches
- Irregular periods, unwanted hair growth or other hormonal symptoms with the skin change
Conditions that can look similar
- Post-inflammatory hyperpigmentation, erythrasma, terra firma-forme dermatosis and confluent and reticulate papillomatosis can all resemble acanthosis nigricans, and ingrained dirt is the assumption most people make first. Rarely, an extensive change that develops rapidly in an adult, particularly alongside weight loss or involvement of the lips and palms, can accompany an internal illness and should be assessed promptly. Anything changing, bleeding, spreading or not settling should be seen in person.
Self-Care & Prevention
Caring for Dark, Velvety Skin Between Appointments
Home care for acanthosis nigricans has a limited but real role: keeping the folds moisturised and reducing friction helps the surface, whereas scrubbing makes it worse. The measures that change the condition most are the ones aimed at the underlying cause, which is why assessment comes first.
Do
- Have new or spreading patches assessed medically within a few weeks, not simply treated cosmetically
- Moisturise the affected folds twice daily, morning and night, to keep thickened skin softer
- Give a topical regime a consistent four to six weeks before judging whether it is working
- Follow the advice you are given on weight, activity and repeat blood tests, usually reviewed at three to six months
Avoid
- Scrubbing with exfoliating gloves or brushes — the patches darken within a week or two of it
- Household bleach, lemon juice and other home remedies, which can burn folded skin in minutes
- Unregulated skin-lightening creams bought online, some of which contain mercury or strong steroids
- Daily shaving or waxing of the affected folds — leave at least a week between passes
This is general guidance and does not replace individual assessment. Because acanthosis nigricans can be linked to an underlying medical condition, treating the appearance at home is not a substitute for finding out why it has appeared.
Why Patients Choose Faciem
Dark, Velvety Skin Assessed by a Doctor, Not Only Treated
Acanthosis nigricans looks like a pigmentation problem and is often approached as one. It is frequently a medical sign as well, and the improvement tends to hold better once the reason it appeared is understood and being addressed.
- Assessed by Dr Prasad, a GMC-registered doctor, not treated as pigment alone
- Blood tests arranged where the history and examination indicate them
- Topical regimes chosen for deeper skin tones, where over-treatment darkens skin further
- Onward referral where a metabolic or hormonal condition needs longer-term management
Experience & Expertise
Why Acanthosis Nigricans Needs a Medical Opinion
Acanthosis nigricans is one of the few skin changes that is more useful as information than as a complaint. It is often the first outward sign that insulin is running high, and it can appear years before blood sugar itself becomes abnormal, which makes it an opportunity rather than a cosmetic nuisance. Treating it with lightening products alone improves the visible part and leaves the rest unexamined. There is a second reason a doctor should see it. A small number of adults develop it quickly and extensively, and in that pattern it can accompany an internal illness that needs finding. Separating the common presentation from the uncommon one rests on the history: how fast it came on, where it sits, and what else has changed. Dr Prasad examines the skin, takes that history, arranges blood tests where they are indicated, and treats the appearance alongside the cause.
- Dr Anamica Prasad — MBChB (1999), Dip Dermatology (2001), MRCGP, DFFP, DRCOG · a GMC-registered doctor
- Member of the Joint Council for Cosmetic Practitioners (JCCP), British Medical Laser Association (BMLA), Royal Society of Medicine and the Aesthetic Complications Group
- Clinic operated by Derma Medical UK Ltd, registered with the Care Quality Commission for diagnostic and screening procedures, surgical procedures, and treatment of disease, disorder or injury · CQC Location ID 1-25573003746
- Face-to-face medical consultation and examination before any treatment is prescribed
- 20 years’ experience in dermatology, including pigmentation and skin disease in deeper skin tones
Patient Reviews
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Acanthosis Nigricans FAQs
Your Questions, Answered
Patients bring the same few worries to clinic about acanthosis nigricans — whether it means diabetes, why the patches will not scrub off, and what can be used during pregnancy. The short answers are below; anything more personal belongs in your consultation.
What causes dark, velvety skin in the neck and armpits?
Dark, velvety thickening in the body folds is usually acanthosis nigricans, most often driven by high insulin levels acting on the skin. Excess weight, polycystic ovary syndrome, thyroid problems and certain medicines are other recognised causes. Rarely, a rapid onset in an adult accompanies an internal illness, which is why assessment matters.
Can acanthosis nigricans be treated during pregnancy or while breastfeeding?
Yes, but the regime changes. Topical retinoids and hydroquinone are avoided throughout pregnancy and breastfeeding, so treatment for acanthosis nigricans shifts to gentler options such as azelaic acid, urea-based moisturisers and light exfoliation, reviewed again once feeding has finished. Patches that appear or darken during pregnancy also warrant a blood sugar check, because gestational diabetes and polycystic ovary syndrome both involve insulin resistance. Tell Dr Prasad at the consultation if you are pregnant, trying to conceive or breastfeeding.
Can I exercise or go to the gym with acanthosis nigricans?
Yes, and exercise is one of the few measures that acts on the cause of acanthosis nigricans rather than the appearance, because improving insulin sensitivity is what allows the patches to lighten. The usual target is 150 minutes of moderate activity a week. Shower and dry the folds properly within an hour of finishing, as sweat and damp fabric trapped in a fold add to the chafing, and change out of a tight collar rather than sitting in it.
Why will the dark skin on my neck not wash off?
The colour of acanthosis nigricans sits within thickened skin, not on its surface, so washing cannot shift it. The condition deepens the skin’s normal lines into velvety ridges that hold shadow and look ingrained with dirt. Scrubbing only irritates the area and darkens it further. One lookalike, terra firma-forme dermatosis, does wipe away with an alcohol swab — a simple test a doctor can carry out in clinic.
Does dark, velvety skin mean I have diabetes?
No. Acanthosis nigricans is associated with insulin resistance, which is not the same thing as diabetes and often exists without it. Many people with the skin change have entirely normal blood sugar. It is still worth investigating, because it can appear before other signs and a simple blood test settles the question.
Can children get acanthosis nigricans?
Yes. Acanthosis nigricans occurs at any age, and in children and teenagers it is most often linked to insulin resistance and excess weight. A rarer familial form also appears in childhood with no metabolic cause behind it. A child developing dark, velvety patches in the neck or armpits should be assessed, because checking for insulin resistance early is simple and genuinely useful.
How quickly does acanthosis nigricans treatment show results?
Most patients notice early improvement after around two weeks of consistent topical treatment for acanthosis nigricans, with better results at four to six weeks. The thickened texture responds more slowly than the colour, and long-standing patches take longer still. Once the skin is under control, a maintenance skincare regime helps hold the improvement, particularly while the underlying cause is being managed.
Sources & Further Reading
These are general sources of patient information and do not replace individual medical assessment. Your own diagnosis and treatment plan come from an in-person consultation.
Acanthosis Nigricans in Kensington, London
A Doctor-Led Clinic in the Heart of Kensington
The clinic sits at 7 Kensington Church St, open Monday to Saturday, 10am–7pm, with High Street Kensington station a few minutes away on foot, Notting Hill Gate about ten, and Kensington council underground parking close by. Acanthosis nigricans is a condition we ask to see in person: the velvety texture and the pattern of folds involved carry as much diagnostic weight as the colour, and neither comes across in a photograph. Most patients reach us easily from Chelsea, Holland Park, South Kensington and the wider stretch of West London.
Plan Your Visit
- Faciem Dermatology & Medical Clinic
- Phone: +44 20 7131 3539
- 7 Kensington Church St, London W8 4LF, United Kingdom
- Tube: High Street Kensington (few minutes’ walk) · Notting Hill Gate (~10 minutes)
- Parking: Kensington council underground car park nearby
- Open Monday–Saturday, 10am–7pm · Sunday closed
- Consultations bookable online; blood tests arranged where indicated
- Consultation-first — no treatment without medical assessment
- Serving Kensington, Chelsea, Notting Hill & Central London
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Faciem Dermatology & Medical Clinic · Kensington
Have the Cause Found, Not Just the Colour Treated
Book a consultation with Dr Prasad at our Kensington clinic to have the skin examined, arrange any blood tests that are indicated, and plan treatment for the appearance alongside the cause.
Prefer to talk? +44 20 7131 3539