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.
What are the 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 condition causing scalp itching is necessary to effectively get rid of the itchy scalp.
Dry Scalp Causing Itchy 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.
Itching of the scalp due to dryness is more common during cold, winter months.
Dandruff as a Cause of Itchy Scalp
While mild dandruff may not cause much itching on the scalp, superadded yeast infection will cause itchy scalp in the mild to moderate types of dandruff.
The scaling of dandruff is generalized over the scalp. When severe, the scaling may extend to the eyebrows, ear canal, front and back of chest etc.
Scalp Itching Caused by 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. Seborrheic dermatitis is can be considered as the inflammatory type of dandruff.
Scalp Psoriasis: An Important Cause of Itchy Scalp
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.
Though at times scalp psoriasis can occur without scaly rashes elsewhere in the body, in most cases other areas of the body is also involved.
Contact Dermatitis
Allergy to certain scalp and hair applications (creams, lotions, gels, shampoos, hair dye etc) can result in severe itchy scalp with oozing, crusting and scaling.
A history of itchy scalp following use of some applications on the scalp is an indicator that the itching is caused by contact allergy.
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 wet hair before it is dried properly. This creates a perfect environment for the lice to flourish.
Severe lice infestation can cause secondary bacterial infection, oozing, crusting and other inflammatory 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.
Scalp ringworm can cause severe itching resulting in further patchy loss of hair. The skin shows mild to moderate scaling, crusting and oozing. Inflammatory reaction of the tinea capitis can cause boggy swelling in the area, known as kerion.
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 chronicus.
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.
The itchy scalp in lichen planus can cause patchy scarred hair loss with underlying violaceous skin.
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
Hanish Babu - Dr.Hanish Babu, MD is a dermatologist and a feature writer on Suite101.com with more than 200 articles related to skin diseases on the ...
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