Medically reviewed guide · Last updated: 1 August 2026 · Reading time: approx. 8 min

Itchy Scalp: Dandruff, Psoriasis or a Hair-Care Mistake?

The most common causes compared

The causes in detail

Seborrhoeic eczema: greasy, yellowish scales

The most common cause. The yeast Malassezia is involved; it lives on every scalp and feeds on skin oils. Some people react to its metabolic products with inflammation and accelerated keratinisation — the result is greasy, yellowish, coarse scales on reddened skin. Typically the eyebrows, the creases beside the nose and the beard area join in; it runs in flares, often worse in winter and under stress. It has nothing to do with hygiene.

Dry scalp from over-washing

Fine, white flakes without redness, plus a feeling of tightness after washing: usually not a disease at all, but a dried-out skin barrier — see the separate section below and the article on dry skin.

Scalp psoriasis: sharply defined and thick

In psoriasis, the outer layer of the skin renews itself far too quickly. On the scalp this produces sharply defined, raised, thick plaques with silvery-white scaling. The most important distinguishing feature: the patches do not stop at the hairline but reach onto the forehead, the back of the neck or behind the ears. Nail changes and plaques on the elbows or knees are further clues. The order matters: first lift the thick scale, then anti-inflammatory treatments can work.

Atopic eczema: the itch that comes at night

Atopic eczema rarely affects the scalp on its own, but it certainly joins in: poorly defined, dry, reddened areas, with the itching at its worst in the evening and at night. Clues to the underlying tendency are hay fever, asthma or eczema in the crooks of the elbows and behind the knees.

Contact allergy: when a product is the trigger

Hair dyes are the classic culprit; p-phenylenediamine (PPD) is one of the best-known contact allergens. The delay is typical: not during the colouring itself, but hours to two days later the hairline, ears and neck turn red, blisters form, and the skin weeps and itches. Perming agents, fragrances and preservatives are also possible. The reaction can spread as a skin rash, occasionally as hives. If you have reacted once, make a note of it — the next contact is usually more severe.

Head lice: more common than many people think

Head lice have nothing to do with cleanliness; they are passed on by direct hair-to-hair contact. The itching is localised, often at night, with scratch marks at the nape. What matters is not the fast-moving lice but the nits glued firmly to the hair: flakes can be brushed off, nits cannot.

Systemic causes: when the skin is only the messenger

Itching can originate outside the skin. In chronic kidney disease, distressing itching without a rash is a well-known problem; in diabetes the skin is more often dry and more prone to fungal colonisation. Thyroid and liver disease as well as iron deficiency belong on the list too. The common denominator: it is not only the scalp that itches. Put this in context under itching.

Hair-care mistakes: when the treatment is the problem

This point deserves a section of its own, because it describes the most common avoidable case. It itches and it flakes, so you wash more often and hotter — and that is exactly what strips away the protective layer of oil. The skin dries out, flakes more finely, itches more, and you wash more often still.

• Water that is too hot: it dissolves skin oils particularly thoroughly. Lukewarm is enough — after a week of getting used to it, most people find it more pleasant anyway.
• Washing too often with harsh shampoos: “deep cleansing” products are not suitable for an irritated scalp. A mild shampoo, used sparingly and applied to the scalp rather than to the lengths, is plenty.
• Hot blow-drying from close up: a cooler setting, more distance and towel-drying your hair well beforehand often help noticeably.
• Styling at the roots: dry shampoo, spray and gel belong in the lengths — residues irritate.
• Constantly switching products: if you try something new every few days, you never give anything a chance to work.

Self-tests: first clues at home

These observations do not replace a diagnosis, but they will make the conversation at your appointment more precise.

• The flake test: greasy-yellowish and coarse (seborrhoeic eczema) or fine, white and dry (a dried-out scalp)?
• The hairline test: do the scaling patches reach beyond the hairline onto your forehead or the back of your neck? That points towards psoriasis.
• The whole-body test: does only your scalp itch, or your trunk, arms and legs as well? Itching everywhere without a rash shifts the suspicion towards internal causes or medicines.
• The timing test: did the itching start days to weeks after beginning a new medicine, or after colouring your hair? Note the date — that trail belongs in the conversation.

Warning signs: when not to wait

• Itching all over your body without a rash, lasting weeks
• Alongside it, unintended weight loss, night sweats or fever
• Weeping, crusted or pus-filled areas
• Rapidly increasing, circular hair loss in the inflamed areas
• Swelling of the face, lips or tongue, or breathing difficulty after a hair treatment

The treatment pathway: step by step

Treatment proceeds in stages; the decision about treatment is made by the practice looking after you.

1. Declutter your hair care. Wash lukewarm, use a mild shampoo, wash less often, turn the hairdryer down — consistently for two to four weeks.
2. Antifungal shampoo, left on to work. Ketoconazole, ciclopirox or selenium disulfide target the Malassezia yeast. How you use it is decisive: lather up, leave it on for three to five minutes (follow the patient information leaflet), then rinse out. Two to three applications a week over several weeks are usual, then less often to maintain the effect.
3. Lift the scale. Shampoos, solutions or oils containing salicylic acid loosen thick deposits. In psoriasis this is the necessary first step; on a very dry scalp salicylic acid can itself irritate and should not be used long-term.
4. Damp down the inflammation briefly. Solutions and foams containing a corticosteroid work quickly against redness and itching; ointments make the hair sticky. They are intended for a few days to a few weeks, then tapered off. Details in the guide to cortisone.
5. Tar preparations as an alternative. Coal tar shampoos are still used for psoriasis and stubborn seborrhoeic eczema; they have a characteristic smell, can stain and increase sensitivity to light.
6. Bring in dermatology. At the latest when nothing improves after four to six weeks, when patches reach beyond the hairline, when hair falls out or when the itching disturbs your sleep. Take the products you have tried and a complete list of your medicines with you — the guide preparing for your doctor's visit gives you a structure for that.

The medication angle: when the itching comes out of a tablet

Itching is one of the most common side effects there is — and it does not always appear with a rash. That is precisely what makes it hard to attribute. The guide side effects of medicines helps to put it in context.

Opioids: histamine release without an allergy

Opioid painkillers such as tramadol and tilidine can release histamine from mast cells. The result is itching, often on the face, nose and scalp — without any allergy being present. The difference matters: itching on its own is a known and often temporary side effect; itching with weals, facial swelling or breathing difficulty is an emergency.

Blood pressure medicines and antimalarials

ACE inhibitors such as ramipril or lisinopril are known for the dry cough, but they can also cause skin reactions and itching — and, rarely, angioedema with swelling of the lips and tongue, which has to be treated immediately. Water tablets such as hydrochlorothiazide increase sensitivity to light. Chloroquine-type antimalarials are known for pronounced, at times distressing itching, which particularly often affects people with darker skin.

Other common triggers

• Antibiotics such as amoxicillin — itching and rash are typical reactions.
• Gout medicines such as allopurinol — skin reactions need to be taken particularly seriously here.
• Corticosteroid preparations such as prednisolone or mometasone — they help against itching, but used for too long they can thin the skin and trigger a flare once they are stopped.

Against the itching itself, antihistamines such as cetirizine work when histamine is involved — where the itching is caused by dryness or by kidney disease, the effect is often disappointing. If a fungus is involved, active ingredients such as clotrimazole come into consideration; the choice is made by the practice.

How to prevent an itchy scalp

• Lukewarm instead of hot — the simplest and most effective change there is.
• One shampoo, four weeks — that is the only way to tell whether something works.
• Take maintenance treatment seriously — one application every one to two weeks keeps many flares small.
• Test before you colour — do the manufacturer's tolerance test 48 hours beforehand, especially after an earlier reaction.

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