Itching of the Scalp

Common causes of an itchy scalp

Dandruff and seborrheic dermatitis

Dandruff causes white or yellowish flakes and mild itch. Seborrheic dermatitis is a more inflamed version, with red, greasy, scaly patches on the scalp, eyebrows, sides of the nose and behind the ears. Both are linked to an overgrowth of a normal skin yeast, Malassezia, and an oversensitive reaction to it. They worsen in winter, with stress, and when hair is washed less often.

Scalp psoriasis

Psoriasis on the scalp forms thick, well-defined, red plaques with silvery-white scales, often extending past the hairline onto the forehead, neck or behind the ears. It can itch intensely. Look for psoriasis elsewhere: elbows, knees, lower back and nail pitting.

Head lice

Head lice are common in school-age children. The itch is caused by an allergic reaction to louse bites and may take weeks to start. Look for live lice moving close to the scalp and nits (eggs) firmly stuck to hairs within about 1 cm (half an inch) of the scalp, especially behind the ears and at the nape. Nits do not brush off like dandruff.

Allergic and irritant reactions

Contact dermatitis from hair dye (especially paraphenylenediamine, or PPD), bleach, perm solutions, fragrances and preservatives in shampoos causes itching, redness and sometimes swelling, which can spread to the forehead, ears and eyelids. A severe reaction can cause marked facial swelling.

Dry scalp

Cold weather, hot showers, frequent washing and harsh shampoos dry the scalp, causing small, white, dry flakes and itch without much redness or greasiness.

Scalp ringworm (tinea capitis)

Tinea capitis is a fungal infection mainly affecting children. It causes itchy, scaly patches with broken hairs ("black dots") and patchy hair loss. A painful, swollen, pus-filled patch (kerion) can develop. It needs oral antifungal medicine, since creams do not reach the hair roots.

Folliculitis

Folliculitis is inflammation of the hair follicles, causing itchy or tender red bumps and pustules on the scalp. It may be bacterial or yeast-related.

Other causes

• Lichen planopilaris and other scarring hair loss conditions: itching or burning with shiny, smooth bald patches.
• Atopic eczema: dry, itchy, inflamed scalp, often with eczema elsewhere.
• Nerve-related itch: scalp itch without a rash, sometimes linked to neck problems, stress or "scalp dysesthesia."
• Body-wide itch: from liver or kidney disease, iron deficiency or thyroid problems.

Telling the causes apart

Itchy scalp and hair loss

Scratching itself does not usually cause permanent hair loss, but some causes of itch also cause hair loss: tinea capitis, scarring alopecias such as lichen planopilaris, severe psoriasis and seborrheic dermatitis (temporary shedding). Itch with patchy hair loss should be seen by a doctor or dermatologist, because early treatment of scarring conditions can save hair follicles.

How it is diagnosed

A doctor will look closely at the scalp and hair, sometimes with a magnifier (dermatoscope), ask about products, family members with lice, and skin conditions elsewhere. Tests may include fungal scrapings or hair samples for tinea capitis, patch testing for suspected allergy, and occasionally a scalp biopsy for hair loss.

Itchy scalp treatment

Medicated shampoos

Leave the shampoo on for about 5 minutes before rinsing. Use it 2 to 3 times a week until settled, then once a week to prevent return. Rotating between two types can help.

Other treatments

• Psoriasis and severe seborrheic dermatitis: steroid scalp lotions, foams or shampoos, and vitamin D-based treatments. Severe psoriasis may need tablets or injections.
• Head lice: permethrin, dimethicone or other approved lice treatments, used exactly as directed, plus wet combing with a fine-toothed lice comb. Check all household members and treat only those with live lice.
• Contact dermatitis: stop the product, wash out residue, and use a steroid lotion. Seek urgent help for facial swelling.
• Tinea capitis: oral antifungal medicine for several weeks, plus antifungal shampoo to reduce spread.
• Dry scalp: gentle, fragrance-free shampoo, lukewarm water, and a light scalp oil or moisturizer.

Avoid scratching with nails, which can break the skin and lead to infection.

Frequently asked questions

Why is my scalp so itchy?

The most common causes are dandruff and seborrheic dermatitis. Others include scalp psoriasis, head lice, reactions to hair dye or products, dry scalp and fungal infection. Looking at the type of flakes, any rash, and whether others at home are itchy helps identify the cause.

What is the best shampoo for an itchy scalp?

For dandruff or seborrheic dermatitis, shampoos containing ketoconazole, selenium sulfide or zinc pyrithione work best. For psoriasis, coal tar or salicylic acid shampoos help. Leave them on for about 5 minutes before rinsing.

Can an itchy scalp cause hair loss?

Itch from dandruff rarely causes lasting hair loss, though heavy scratching can break hairs. Some itchy conditions, such as scalp ringworm, lichen planopilaris and severe psoriasis, can cause hair loss, so itch with bald patches should be checked.

How do I know if I have lice or dandruff?

Dandruff flakes fall or brush off easily. Lice eggs (nits) are glued to the hair shaft close to the scalp and do not slide off. Finding live lice with a fine-toothed comb confirms head lice.