Dandruff, Dry Scalp and Seborrheic Dermatitis

What these terms mean

Dandruff is a common, harmless condition that causes white flakes of skin on the scalp and in the hair, sometimes with a dry, itchy scalp. [1] Seborrheic dermatitis is a related inflammatory condition with scaling, redness and itching, most often on the scalp, face, chest, back, armpits and groin. [2] A "dry scalp" is a common phrase, but flaking and itching can have several causes, so the label alone does not tell you what treats it. Evidence labels: established recommendation, promising but limited, mixed, insufficient evidence.

Causes

The NHS says dandruff is not caused by poor hygiene, although it may be more noticeable if you do not wash your hair regularly. It may be caused by a yeast that naturally lives on the skin and by skin conditions such as eczema, and stress and cold weather may make it worse. [1] For seborrheic dermatitis, the skin changes are thought to result from an inflammatory response to a common skin organism, Malassezia yeast. [2]

Established care

Dandruff (NHS): use an anti-dandruff shampoo with ketoconazole, coal tar or salicylic acid; use it for up to 4 weeks to see whether it helps, and you may need to try more than one type. [1] A pharmacist can explain how to use it. [1]

Seborrheic dermatitis: a review in American Family Physician says topical antifungals such as ketoconazole are the mainstay for the face and body, over-the-counter shampoos are a starting point for scalp disease, and corticosteroids or calcineurin inhibitors should be used only for short periods because of possible side effects. [2] This is an established recommendation. Prescription decisions belong with a clinician.

Conditions that look like dandruff

The NHS lists these possible causes of scalp flaking: seborrheic dermatitis, tinea capitis (ringworm, which can come with patchy hair loss), eczema, contact dermatitis (for example a reaction to hair dye, sprays or gels) and psoriasis. [1] MedlinePlus lists shampoos and hair dyes among common irritants and hair dyes and permanent wave solutions among allergens. [3] See Psoriasis, Eczema and Contact dermatitis.

Natural options

Proper evidence not found in the sources I checked for herbal, oil or essential-oil scalp treatments of dandruff. Tea tree oil is a recognized contact allergen on skin ([4]), so apply caution; see Tea tree oil and Essential oil safety. See also Natural ingredient safety.

When to get help

The NHS says to see a GP if symptoms persist after at least 4 weeks of anti-dandruff shampoo, if dandruff is bad or the scalp very itchy, if the scalp is red or swollen, or if there are flaky itchy patches on the face or elsewhere. [1] Flaking with patchy hair loss can have other causes; see Hair shedding and thinning and Skin and hair safety.