logo Disorders of hair and scalp

Follicular skin diseases

Disorders of hair and scalp


  • Diagnose common disorders affecting hair and scalp.
  • Be familiar with the range of treatments used for these disorders.

Key points

  • Shedding is most often due to telogen effluvium.
  • Telogen effluvium may follow pregnancy, weight loss, fever or stress.
  • Diffuse hair thinning is most often due to male pattern balding in men (androgen-dependent) and female pattern balding (nonandrogen-dependent) in females.
  • Diffuse hair thinning may be due to systemic lupus erythematosus, syphilis, iron deficiency, hypothyroidism and alopecia areata.
  • Alopecia areata is an autoimmune skin disease that most often starts in childhood or young adult life.
  • It usually results in round smooth bald patches, occasionally resulting in total hair loss.
  • Limited localised disease is best managed by intralesional corticosteroid injections.
  • Erythema, scaling, pustules or scarring with hair loss may be due to tinea capitis, discoid lupus erythematosus, folliculitis or lichen planus.
  • Scaly scalp diseases include seborrhoeic dermatitis, psoriasis, lichen simplex.
  • Hirsutism is excessive hair growth in females in a male pattern due to endogenous or exogenous androgens or end-organ sensitivity (idiopathic hirsutism).
  • Physical methods of hair removal include shaving, depilatories, waxing, electrolysis and laser epilation.
  • Medications causing hypertrichosis include ciclosporin, minoxidil and antiepileptics).
  • Hypertrichosis may be due to hypercorticism, hypothyroidism, porphyria cutanea tarda, and anorexia nervosa.


This section is concerned with the following:

Hair shedding

Hair loss may refer to excessive shedding or baldness (or both). Shedding is most often temporary and due to telogen effluvium (hair bulbs present), but may also be during anagen (no hair bulb) if due to alopecia areata or provoked by a drug (e.g. retinoid, hormone, anticoagulant, statin, cytotoxic). Telogen effluvium may follow two or three months after a provoking event, most often parturition, sudden weight loss, blood loss, fever or “stress”. The shedding stops within a few months but it may take a couple of years for the hair bulk to appear normal. Chronic telogen effluvium arises when the hair cycle has sped up so that the anagen phase is shorter; identify and treat iron deficiency (test ferritin) and hypothyroidism. Most cases are women with diffuse non-androgenic pattern balding.

Telogen effluvium

Telogen effluvium

Diffuse alopecia

Diffuse hair thinning is most often due to male pattern balding in men (androgen-dependent) and female pattern balding (nonandrogen-dependent) in females. However, it may accompany internal disease (particularly systemic lupus erythematosus and syphilis). Thin fragile hair may accompany iron deficiency. Coarse dry hair may be due to hypothyroidism. In the absence of other symptoms, consider severe alopecia areata.

Pattern balding (male)

Pattern balding (female)

Pattern balding (female)

Localised alopecia

Balding can be reversible, but if there is scarring it is permanent. Alopecia areata is the most common cause of one or more areas of localised baldness on the scalp and other hair-bearing areas. It is an autoimmune skin disease and is more common in those affected by, or with a family history of, vitiligo, diabetes and thyroid disease. It is also more common in Down’s syndrome. Although the onset may be at any age, it most often starts in childhood or young adult life.

The scalp appears normal in alopecia areata, but there may be broken-off short hairs resembling exclamation marks (!). In about 5% all hair from the head is lost (alopecia totalis) and in 1% the body hair is also lost (alopecia universalis). In 80% there is regrowth within a few months, but it may be lost elsewhere at the same time or later. Prognosis seems less good in very young children, if the initial hair loss is severe and extensive or affecting facial areas. The nails may be affected resulting in pitting and ridging.

Alopecia universalis

Localised alopecia areata with marginal regrowth after triamcinolone injections

Loss of eyebrows in severe alopecia areata

There is a strong placebo effect of treatment because spontaneous regrowth may occur at any stage. It is therefore hard to assess the value of individual treatments. Limited localised disease is best managed by 6 to 8-weekly intralesional corticosteroid injections (maximum 20mg per visit) or ultrapotent topical steroid cream / gel under occlusion.

The The Ministry of Health provides a subsidy to obtain a wig, if medically necessary.

If bald patches are accompanied by inflammation (erythema, scaling, pustules) consider other reasons for hair loss:

Cicatricial alopecia due to discoid lupus erythematosus

Pseudopelade (a scarring alopecia without obvious inflammation)

Severe folliculitis decalvans


These disorders may result in scarring (cicatricial alopecia) in which there is shiny pale skin and reduced or absent follicular orifices.

Hair shaft abnormalities

These are rare and diagnosed by light or electron microscopy. They present as thin, short, or unruly hair in young children. The most common abnormalities are:

‘Spangled’ hair shaft abnormality

‘Loose anagen’ syndrome

Skin diseases affecting the scalp

Skin diseases that favour the scalp may not cause any hair loss, although when they are very severe this may occur.

The most common conditions affecting the scalp are:

Seborrhoeic dermatitis
Dandruff (non-inflammatory) or pityriasis capitis: diffuse scaling
Ill-defined inflammatory plaques with yellowish scale
Diffuse or localised well-defined erythematous plaques with silvery scale
Lichen simplex
Well demarcated lichenified intensely itchy plaques, usually on occiput
Chronic scattered and irritable follicular pustules
Solar keratoses (and skin cancers)
Adherent scaly lesions leading to squamous cell carcinoma

Pityriasis amiantacea: sticky scale due to underlying psoriasis or seborrhoeic dernatitis

Infantile seborrhoeic dermatitis (cradle cap)

Scalp folliculitis

Solar keratoses and an early squamous cell carcinoma on bald scalp

Excessive hair

Hirsutism is excessive hair growth in females in the beard area, around the nipples, in a male pattern on the abdomen (diamond-shaped pubic hair) and often elsewhere. It is more common in darker skinned Europeans or Middle-Eastern women. It causes a great deal of distress.

Hirsutism is the result of the conversion of fine vellus hair to coarse terminal hair induced by androgens. These may be endogenous (adrenal, pituitary or ovarian origin) or exogenous (androgenic drugs) – excessive androgens will also result in virilism, amenorrhoea and infertility. Investigations should include:

However, end-organ sensitivity in idiopathic hirsutism is more common, in which investigations indicate hormone status to be normal.

Idiopathic hirsutism

Physical methods of hair removal include:

Medical treatment may be helpful: spironolactone, ethinyloestrodiol/cyproterone contraceptive pill or 50-200mg cyproterone for days 1 to 10 of the menstrual cycle.

Hypertrichosis may be congenital (hairy congenital naevi, hypertrichosis lanuginose and familial hypertrichosis) or acquired. Acquired hypertrichosis may be due to medications (ciclosporin, minoxidil, antiepileptics) or disease (hypercorticism, hypothyroidism, porphyria cutanea tarda, anorexia nervosa). Medical treatment should be directed at the underlying disease.

Congenital hypertrichosis lanuginosa

Becker naevus (localised hairy epidermal naevus of late onset)

Hypertrichosis due to ciclosporin prescribed for severe psoriasis