Itchy scalp can be caused by a number of diseases, which are diagnosed by the history and nature of scaling, duration of itching, severity of itching, extent of scales and presence of skin rashes elsewhere on the body.
Causes of Itchy Scalp
The commonest causes of itchy scalp are dry scalp, dandruff, seborrheic dermatitis, scalp psoriasis, contact dermatitis, head lice infestation, ring worm of the scalp, tinea amiantacea, lichen planus, hair follicle inflammation, neurogenic excoriation and pyogenic infection of scalp. Needless to say, a definite diagnosis of the diseases causing scalp itching is necessary to effectively get rid of the itchy scalp.
Dry Scalp
Dry scalp is one of the overlooked causes of itchy scalp. This may be caused by harsh shampoos, hair lotions or tinctures with alcohol as base or following frequent washing.
Dandruff
While mild dandruff may not cause much itching on the scalp, superadded yeast infection will cause itching of mild to moderate severity. The scaling of dandruff is generalized over the scalp.
Seborrheic Dermatitis
Seborrheic dermatitis shows greasy scales throughout the scalp. The underlying skin may be reddish. In severe cases, red scaly rashes may be present on the sides of the nose, chest and back. The scalp itching in seborrheic dermatitis can be moderate to severe.
Scalp Psoriasis
Scalp psoriasis, in contrast to seborrheic dermatitis, has thick scales with scattered plaques at different places of the scalp. Scraping off the scales reveals bleeding points, the Auspitz’ sign. Itching is variable in scalp psoriasis.
Contact Dermatitis
Some scalp and hair applications (creams, lotions, gels, shampoos, hair dye etc) can present as severely itchy scalp with oozing and crusting and scaling. The history of new applications followed by the itchy scalp clinches the diagnosis in most cases.
Head Lice Infestation (Pediculosis Capitis)
Pediculosis capitis or head lice infestation is a common cause of itchy scalp in girls and young women who tie their hair before it is dry and create a perfect environment for the lice to flourish. Severe lice infestation can cause secondary bacterial infection, oozing, crusting and dermatitis changes on the scalp, neck and forehead. Finding the louse and its egg confirms the diagnosis.
Ring Worm of the Scalp (Tinea Capitis)
Ring worm of the scalp is usually seen in children, and rarely in adults. There is circumscribed and patchy scaling and itching with broken hairs or hair fall in the area.
Pityriasis Amiantacea (Tinea Amiantacea)
Pityriasis amiantacea is thought to be a hypersensitivity response to a number of scalp diseases, like scalp psoriasis, seborrheic dermatitis or lichen simplex. Tinea amiantacea is a misnomer as fungal infection is rarely a cause for P. amiantacea. There is a thick yellow crusty flaking of the scalp along with matting of the hairs in the affected areas. Scaling is more prominent than itching in P.amiantacea.
Lichen Planus
Lichen planus can affect the scalp at times, and is known as lichen plano pilaris. Redness, itching, hair loss and scarring are the features of lichen planus.
Hair Follicle Inflammation
Hair follicles inflammation or infection, known as folliculitis can occur on the scalp due to yeast or bacteria. Itchy scalp and painful, scattered and infected bumps are the main features of scalp folliculitis.
Neurogenic Excoriation
Neurogenic excoriation or lichen simplex is another cause for itchy scalp and is related to stress and anxiety. Habitual scratching leads to thickening and hair loss to a localized area of the scalp, usually on the sides.
Pyogenic Infection of Scalp
Bacterial infection of the scalp is common in malnourished children. Itchy, flaky crusts with yellowish discharge mat the hairs together in pyogenic infection of the scalp.
Next: Itchy Scalp Remedies
Reference
- Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, Fifth Ed, 2005
- Rook’s Textbook of Dermatology, 7th Edition, 2004
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