By Vitalii Prisacari, VTCT Skills Level 3 Diploma in Women's Hairdressing, including the Level 4 Hair and Scalp unit, State Registered Graduate Hairdresser, founder of Matted Hair London. Helped 1,000+ people since 2020. Reviewed 2 October 2026.
The short answer
Excessive matting of the hair is referred to as plica polonica. Dermatologists also call it plica neuropathica or acute hair matting. It is a rare condition in which scalp hair twists, felts and fuses into a stiff, solid mass that will not separate with a comb or fingers.
What Is Plica Polonica?
Plica polonica is the medical name for felted hair: hair matted so completely that it behaves like a single object. The strands wind around each other, the cuticle scales on their surfaces lock together, and the mass is cemented with sebum, sweat, dead skin and, in cases left for a long time, the debris of infection.
Plica neuropathica came later, when physicians linked the condition to nervous and psychiatric illness. Acute hair matting is the plain clinical term, and Polish plait is still used informally. None of these names says why the hair matted.
A 2022 historical review in the British Journal of Dermatology traces how it spread across Eastern Europe, produced hundreds of papers, and then largely disappeared as hygiene and living conditions improved.
It usually looks like a single oval or elongated mass over the crown and the back of the head, hard to the touch and impossible to part. Some people call it bird's nest hair. When I put my fingers into one at the studio, it feels woven, like felt.
DermNet defines acute hair matting as a sudden solid mass of permanent matting of scalp hair and compares the process to felting in the wool industry, where fibres compact because their rough surfaces catch on each other. Under a dermatoscope, Ghodake, Singh and Thappa (Indian Journal of Dermatology, Venereology and Leprology, 2013) described intertwined hair shafts with honey-coloured concretions that looked like a wrangled mesh of wires. A 2022 report by Patel, Tandel and Nair in the International Journal of Trichology uses the same image, a bird's nest, and the Trichological Society describes the mechanism as cuticle scales interlocking until the shafts are entangled beyond combing.
Where Does the Name Come From?
Plica polonica is Latin for Polish plait. The condition was first described in Poland in the 1800s, when matted, lice-infested plaits over inflamed scalps were common enough among the poor to be treated as a disease in their own right. Early explanations ran from witchcraft to strong emotion.
Most of the people who bring a plica to me in London were ill or grieving when the hair was left.
What Causes Hair to Mat This Severely?
Hair mats this severely when shed strands cannot leave the head and catch on a rough, damaged surface, usually helped along by moisture, friction or an irritated scalp. The published cases I have read, and the ones I have handled, come down to one or more of the five causes below.
01
A damaged cuticle
Healthy hair has a smooth outer layer of overlapping scales. Bleach, heat, harsh shampoo, hard water and vigorous rubbing lift and split those scales, and lifted scales catch on each other like burrs. Hair that turns frizzy after bleach or heat usually has this rough surface.
In a case published in the International Journal of Trichology in 2010, Joshi and Singh examined hair from a plica under the microscope and found ruffled cuticles and superficial fractures along the shaft. Their conclusion was that the changed surface of the hair, not the patient's habits, allowed it to felt. This is why hair that has been bleached or straightened for years can mat in a fraction of the time virgin hair would take.
02
Long hair left unwashed and uncombed
This is the route I see most often. Someone is bedbound, in hospital, depressed, recovering from surgery, or living with dementia, and for weeks nobody brushes the back of their head. I have written separately about matted hair after a hospital stay, matted hair and depression and matted hair in older people and dementia.
In my case files, 42% of all clients since 2020 came to me after depression, illness and hospital stays. Hair sheds 50 to 100 strands a day whether or not it is brushed. After four weeks without a brush, that is up to 2,800 strands with nowhere to fall, and each one can wrap around the strands still growing. Add a pillow, warmth and sweat, and the mass builds from the nape and crown outwards.
03
Sudden heavy shedding
Chemotherapy, some immunosuppressant drugs, severe illness, childbirth and extreme stress can all push large numbers of hairs into shedding at once. Shed hair that stays in the head is what a mat is made of. In the 2010 case above, the plica appeared overnight, following a day of extensive hair loss on azathioprine. A case report of plica polonica during chemotherapy describes the same sequence.
If you are on treatment that is making your hair fall, brush the whole head at least three times a day, roots included. Use a soft brush; my notes on choosing a hairbrush explain which kind. Brushing takes shed hair out before it can wind into the rest.
04
Friction and moisture together
Hair is at its weakest and most mobile when wet, and it can stretch by up to 30% before it breaks. Wet hair pressed under a headscarf, a wig, a hood or a pillow for hours at a time felts the way wool felts in a washing machine. On its own this rarely produces a full plica, but it speeds up every other cause on this list.
05
Infestation and infection
Head lice still turn up in some cases. Scratching damages the cuticle, and the fluid from an irritated or infected scalp dries into the crust that glues a plica together. This is the cause that turns a hair problem into a medical one. If the scalp is sore or weeping, the GP list below comes first.
Rarely, it is deliberate. Some religious ascetics in India grow a plica on purpose, and the case reports from Indian dermatology departments partly reflect that. None of the people I have seen with one chose it.
Is Plica Polonica the Same as Matted Hair?
Not quite. Plica polonica is the far end of matted hair: usually months rather than weeks, the whole mass rather than a patch, and often a scalp that needs looking at. Most of the matted hair I restore is not plica in the strict clinical sense.
The five grades of matted hair I use in the studio run from ordinary tangled hair at Grade 1 to full fusion at Grade 5, and a true plica sits at the top of Grade 5.
| Everyday tangle | Matted hair | Plica polonica | |
|---|---|---|---|
| What you feel | Knots that move | A dense pad against the scalp | One rigid mass, often the whole back of the head |
| Fingers at the root | Go in easily | Cannot get underneath | Nothing goes in; it feels like felt or wood |
| Time to form | Days | Weeks | Weeks to months, or overnight after mass shedding |
| The scalp | Normal | Usually normal, sometimes tender | Frequently sore, smelly, crusted or infested |
| First step | Conditioner and fingers | A specialist assessment | A GP or dermatologist if the scalp is affected; then a specialist |
If you are not sure which column you are in, the complete guide to matted hair walks through each grade with photographs.
How Do Doctors Treat It?
Most often with scissors. Doctors usually cut the mass out and treat the scalp underneath, and the dermatology literature is honest about that.
DermNet lists the options as manual separation of the twisted hairs using an organic solvent in the early stages, or cutting out the matted hair, alongside treating lice, treating any infection with antibiotics, a thorough wash, and shaving the scalp if necessary. Ghodake and colleagues add the step that matters most for the long term: assessing any underlying psychiatric illness, so that the plica does not simply grow back.
That order of priorities is correct for a clinic. In a hospital the scalp is what can become dangerous, and the hair is what can grow back. Nothing on this page argues with a doctor who decides to cut.
For prevention, the same sources recommend what any hairdresser would: regular washing with a mild cleanser, gentle oiling, daily combing and regular trims. Simple, and exactly the things that stop happening when someone is unwell.
Can It Be Saved Without Cutting?
Sometimes. Plica polonica can be separated by hand when the hair and the scalp under it are still sound, and not every one can. Four things decide it, and I check each of them before I start.
Is the hair shaft intact? Hair that has weathered through, like the fractured shafts in the 2010 case, snaps when it is separated. There is no point spending hours saving hair that will break at the first brush afterwards.
Is the mass cemented with exudate or infested? If it is, the scalp comes first and a doctor decides the order. I do not work on an infected scalp.
How long has it been compacting? A mass that formed over weeks around clean, healthy hair usually separates. One that has been pressed under a pillow for a year is a different material.
Can the person sit through it? A plica that covers the whole head is Grade 5 work: 14 hours or more, sometimes two sessions a few days apart. If someone is frail or in pain, I will say so when that is too much to ask of them.
Dematting a plica follows the same step-by-step method for severely matted hair that I use on every severe case. The mat stays dry and nothing goes on it first. I work from the ends up, fingers before any tool, one small section at a time and without pulling. Product goes on a section only once it has started to open.
One case from the studio shows what this looks like in practice. Long, wavy hair had compacted over several months into a single mass covering half of the head. The scalp underneath was healthy, so there was nothing to treat first. It took seven hours of work, and all of the hair was saved; nothing was cut.
Of my clients since 2020, 99% were saved without cutting. Most of them did not have a true plica, so that figure is not a promise for one. If I tell you it needs cutting, it is because saving the hair would cost the scalp, or because the hair itself is already gone and only the shape of it is left.
When to See a GP or Dermatologist
See a GP or a dermatologist before you see me, or anyone else with a comb, if any of these apply:
- the scalp under the mass is sore, weeping, bleeding or has a strong smell;
- you can see lice, nits or crusting;
- the hair fell out suddenly and in large amounts before it matted;
- the person is on chemotherapy, immunosuppressants or long-term steroids;
- the person cannot look after themselves at the moment, whether through mental health, memory or physical illness.
None of this is medical advice. It is the list I use to decide whether a photograph goes to a detangling appointment or to a doctor first. The hair can wait a week. An infected scalp cannot.
Frequently Asked Questions
Excessive matting of the hair is referred to as what?
Plica polonica. Hair-care and cosmetology exams expect that answer, and the Latin means Polish plait. In a dermatology clinic today you are more likely to read plica neuropathica or acute hair matting. All three names describe scalp hair felted into one solid mass that a comb or fingers cannot separate.
Is plica polonica the same as plica neuropathica?
Yes. Plica polonica and plica neuropathica are two names for the same felted mass of scalp hair. The second name came in when doctors noticed how often the felting followed nervous or psychiatric illness, and dermatologists write it more often today. Polish plait and bird's nest hair are the everyday names for it.
Is plica polonica caused by lice?
Not necessarily. Lice turn up inside some cases of plica polonica, but most cases published today follow illness or sudden heavy shedding. Where lice are present, they are treated first, and nothing is done to the hair until the scalp has settled. A pharmacist can advise on a lice treatment that suits the person.
Can hair mat overnight?
It can, though rarely. When a large amount of hair sheds in a single day, the loose strands can felt into the rest over a whole night. During a spell of heavy shedding, brushing the whole head before bed takes that loose hair out. For most people, matting builds slowly over weeks.
Is plica polonica contagious?
No. Felted hair cannot spread from one person to another, because plica polonica is a change in the hair itself, not an infection. Living with or caring for someone who has one will not make your own hair mat. Head lice, which are sometimes found inside a plica, do spread, so they need treating on their own.
Do you have to shave your head for plica polonica?
Not always. Cutting the mass out is the usual hospital route for plica polonica, because a doctor's first concern is the scalp, and that is a fair choice. When the hair shafts are whole and the scalp is healthy, the mass can sometimes be opened by hand instead. If the scalp is healthy, ask for an assessment before anyone reaches for clippers.
Can detangler, conditioner or oil loosen plica polonica?
No. A detangler, conditioner or oil coats the outside of a plica and never reaches the knots inside, and the water in a spray or conditioner tightens what is underneath. In my case files, 89% of recorded home attempts on severe mats made the mat denser. Have it looked at before anyone tries to open it.
Does plica polonica still happen today?
Yes, though rarely. Dermatology journals still publish new cases of plica polonica most years, usually in people who were seriously ill or unable to look after themselves for a while. Doctors no longer treat it as a disease of its own: the felting is the end result of other causes, such as heavy shedding or a damaged cuticle.
Related reading
Send a Photograph, Get an Honest Answer
A photograph of the back of the head, taken in daylight, tells me most of what I need: whether the shafts will hold, roughly how many hours the work would take, and whether cutting would be kinder. If the scalp under it is sore or weeping, see your GP before you send it.
The consultation is free, takes 10 minutes and happens by phone, WhatsApp or video call. I work Monday to Saturday, 9am to 10pm, and in those hours I usually reply within an hour.
Sessions are £100 per hour, at my studio in Catford, SE6, or at home anywhere in London for a £200 surcharge. Klarna and Clearpay both let you pay in 3 at 0% interest. You can see before-and-after photographs of severe cases in the gallery first.
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