Seborrhoeic dermatitis — often spelled seborrheic, and known in its mildest form as dandruff — is the most common inflammatory scalp condition there is, and one of the most common reasons women arrive at this clinic convinced their shampoo is making their hair fall out. Sometimes they’re half right. The condition itself can shed hair; the scratching it provokes reliably breaks it; and the six months spent rotating supermarket shampoos without being told how to use them is usually what turns a nuisance into a hair problem.
This page explains what seborrhoeic dermatitis actually is, when it genuinely costs hair — and the good news underneath: treated properly, it is one of the most fixable causes of shedding we see, and the hair comes back.
- – It’s an inflammatory reaction to Malassezia — a yeast that lives on every scalp — not poor hygiene, and not contagious
- – Greasy yellowish flakes on a red, itchy scalp distinguish it from simple dry scalp, which flakes white and fine — the two are treated oppositely
- – It can shed hair two ways: inflammation pushing follicles into their resting phase, and breakage from months of scratching
- – Hair loss from seborrhoeic dermatitis is almost always reversible once the inflammation is controlled
- – Antifungal shampoos genuinely work — but only with several minutes of scalp contact time, the instruction almost nobody is given
What seborrhoeic dermatitis is — and why your scalp
Malassezia yeasts live on everyone’s skin, feeding on scalp oils. In some people the immune system overreacts to their by-products, producing inflammation, itch, redness and the greasy yellow scale that defines the condition. Why you and not your sister is partly genetic, partly hormonal (it flares where oil production is highest), and partly circumstance — stress, winter, illness and fatigue are classic triggers, which is why it waxes and wanes rather than simply arriving. The severity spectrum is wide: at one end, ordinary dandruff; at the other, thick adherent scale across the scalp, behind the ears and along the hairline and brows. Where you sit on that spectrum decides the treatment — which is exactly what an examination establishes in minutes.
Does seborrhoeic dermatitis cause hair loss?
Yes — by two routes, and the distinction matters for recovery. The first is inflammatory: sustained inflammation around follicles can tip them early into their resting phase, producing a diffuse shed a few months into a bad flare, close cousin to telogen effluvium. The second is mechanical: months of scratching snap hair shafts and traumatise follicles, thinning exactly where the itch is worst. Both are reversible — follicles survive seborrhoeic dermatitis; they do not usually scar. The honest caveat is the company it keeps: a scalp condition and an unrelated hair loss frequently coexist, and we regularly meet women who treated their flakes diligently while pattern hair loss or low ferritin progressed untouched underneath. If shedding continues once the scalp is calm, that’s the signal to look deeper — not to buy a seventh shampoo.
| Seborrhoeic dermatitis | Dry scalp | Scalp psoriasis | |
|---|---|---|---|
| The flakes | Greasy, yellowish, larger | Fine, white, powdery | Thick, silvery, layered scale |
| The skin | Red, itchy, oily areas worst | Tight, itchy, not inflamed | Sharply-edged raised plaques |
| Hair impact | Shedding + breakage in flares — reversible | Breakage from scratching only | Shedding in plaques — see psoriasis page |
| First-line treatment | Antifungal or other medicated shampoos, used correctly | Gentler routine, fewer products | Prescription topicals |
Unsure which you have? That’s normal — misdiagnosed self-treatment is the rule, not the exception, and antifungal shampoo on a genuinely dry scalp makes things worse. One look under magnification settles it.
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Treatment that actually works
The foundation is antifungal shampoo — ketoconazole, selenium sulphide or zinc pyrithione — and the reason it fails so often has nothing to do with the bottle: it needs three to five minutes of contact with the scalp before rinsing, twice weekly, for at least a month. Lathered and rinsed like normal shampoo, it does approximately nothing. Around that foundation: short courses of topical steroid scalp applications calm angry flares fast (prescription-strength where pharmacy options underperform); routine adjustments protect the scalp barrier between flares; and maintenance washing once weekly keeps Malassezia suppressed long-term, because the condition is controlled rather than cured. Where hair has thinned, we treat the recovery too — confirming the follicles are cycling back, supporting regrowth where it’s slow, and photographing progress so you can see the recovery instead of doubting it. And where scale is severe, atypical or simply not responding as it should, a dermatology referral goes out with a proper letter — while your hair care continues here.
Managing the flare cycle: know your triggers
Seborrhoeic dermatitis is a condition you manage into quietness rather than cure, and flares follow patterns worth learning. Season: cold, dry months flare it (many scalps are calm all summer, angry by November — central heating and less UV both contribute). Stress and fatigue: reliably, and often with a one-to-two-week lag that hides the connection. Hormonal shifts: it tracks oil production, which is why it can wake up postpartum or around hormonal changes. Product habits: heavy oils and butters feed Malassezia (it literally eats scalp lipids); occlusive styling products and infrequent washing both give it a friendlier home. Illness: flares after being run down are the rule, not coincidence. You can’t remove every trigger — but knowing yours turns a random-seeming condition into a predictable one, and predictable conditions get pre-empted: many patients learn to step up their maintenance washing at the first November itch rather than after the Christmas flare.
The maintenance rhythm that keeps it quiet
Once a flare is controlled, the pattern that keeps most scalps calm looks like this: medicated shampoo once weekly (with its full contact time — the rule never retires), an ordinary gentle shampoo for other washes, and a planned step-up to twice weekly at the first sign of a flare or entering your trigger season. Topical steroid preparations, if prescribed, are for flares — short, decisive courses — not for daily maintenance. What breaks the rhythm most often isn’t failure but success: the scalp feels normal for two months, the medicated bottle migrates to the back of the shower, and six weeks later the flakes are back and the whole cycle restarts from scratch. The maintenance wash on a calm scalp is the treatment; it just doesn’t feel like one. If quiet maintenance stops working where it used to — or was never achieved despite doing it properly — that’s the signal for prescription-strength options rather than more of the same.
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What happens at your consultation
Trichoscopy first: seborrhoeic scale has a distinctive signature under magnification, and so does the state of the follicles beneath it — which answers the question that actually brought you here, namely whether the flakes and the shedding are the same problem. Bloods are added where the shedding pattern suggests a co-driver worth excluding. You leave with the condition named, the right treatment prescribed, the contact-time technique demonstrated rather than assumed, and a review date. If you’d rather check we are the right clinic for this first, message the clinic on WhatsApp and ask.
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Dr Amy Vowler · GMC-registered GP · GMC 7451097
Message us on WhatsApp or give us a ring. We can't give clinical advice over a message, but we can tell you how the consultation works, what it costs and whether Dr Amy is the right person for you. No obligation, nothing to prepare.
It can — through two routes. Sustained inflammation around the follicles can push them early into their resting phase, causing diffuse shedding during and after bad flares, and months of scratching breaks hair shafts directly. Neither route destroys follicles, which is why this is one of the most recoverable causes of hair loss we treat. The important check is whether the scalp condition is the whole story: seborrhoeic dermatitis frequently coexists with pattern hair loss or a deficiency, and shedding that outlasts a calmed scalp needs the deeper look.
Almost always, yes. The follicles survive — they’ve been irritated and interrupted, not scarred — so once the inflammation is properly controlled and the scratching stops, shed hair re-enters its growth cycle. Expect the sequence to take patience: shedding settles over two to three months and visible density follows over six to twelve, which is why we anchor recovery to photographs rather than daily mirror checks. If regrowth stalls, that’s a reason to be re-examined, not to despair — it usually means a second cause is in play.
Usually one of three reasons. First, technique: antifungal shampoos need three to five minutes of contact with the scalp before rinsing — used like normal shampoo they barely work, and almost nobody is told this. Second, wrong diagnosis: fine white flakes on a tight, non-inflamed scalp suggest dry scalp, which antifungal shampoos can worsen. Third, severity: established seborrhoeic dermatitis often needs prescription treatment alongside the shampoo. Six weeks of correct use without improvement is the point to see a doctor rather than another shelf.
No — and the guilt patients carry about this deserves putting down. It’s an inflammatory overreaction to Malassezia, a yeast that lives on every human scalp; the difference is your immune response, not your washing. Overwashing with harsh products can actually aggravate it by disrupting the scalp barrier. It isn’t contagious, it isn’t caused by dirt, and it flares with stress, winter and hormones — none of which are character flaws.
Severity — they’re the same process. Dandruff is mild seborrhoeic dermatitis: flaking with minimal inflammation, usually manageable with correctly-used antifungal shampoo alone. Seborrhoeic dermatitis proper adds visible inflammation — redness, itch, greasy yellowish scale, sometimes spreading to the hairline, brows and behind the ears — and more often needs prescription treatment. The hair-loss risk sits mostly at the inflamed end, which is why ‘just dandruff’ that’s getting angrier is worth an examination.
When flaking comes with noticeable shedding; when six weeks of properly-used antifungal shampoo hasn’t controlled it; when the scalp is painful, weeping or severely inflamed; or when you’re not actually sure which scalp condition you have — a real possibility, since dry scalp, seborrhoeic dermatitis and psoriasis are treated differently and regularly mistaken for each other. A doctor can prescribe what the pharmacy can’t, treat the hair impact alongside the skin, and refer to dermatology properly in the minority of cases that need it.
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