Dandruff

Dandruff is a skin condition that mainly affects the. Symptoms include flaking and sometimes mild itchiness. It can result in social or problems. A more severe form of the condition, which includes inflammation of the skin, is known as.

The cause is unclear but believed to involve a number of genetic and environmental factors. The condition may worsen in the winter. It is not due to poor hygiene. The underlying mechanism involves the excessive growth of. Diagnosis is based on symptoms.

There is no known cure. The typical treatment is with such as. Dandruff affects about half of adults. Onset is usually at. Males are more often affected than females. Rates decrease after the age of 50.

Signs and symptoms
The signs and symptoms of dandruff are an itchy scalp and flakiness. Red and greasy patches of skin and a tingly feeling on the skin are also symptoms.

Causes
The cause is unclear but believed to involve a number of genetic and environmental factors. The condition may worsen in the winter. It is not due to poor hygiene.

As the layers continually replace themselves, cells are pushed outward where they die and flake off. For most individuals, these flakes of skin are too small to be visible. However, certain conditions cause cell turnover to be unusually rapid, especially in the scalp. It is hypothesized that for people with dandruff, skin cells may mature and be shed in 2–7 days, as opposed to around a month in people without dandruff. The result is that dead skin cells are shed in large, oily clumps, which appear as white or grayish flakes on the scalp, skin and clothes.

According to one study, dandruff has been shown to be possibly the result of three factors:
 * 1) Skin oil commonly referred to as  or  secretions
 * 2) The metabolic by-products of skin micro-organisms (most specifically  s)
 * 3) Individual susceptibility and allergy sensitivity.

Microorganisms
According to a 2016 study, bacteria (mainly and ) are more important to dandruff formation than fungi. Bacterial presence was in turn influenced by water and sebum amount.

Older literature cites the  (previously known as Pityrosporum ovale) as the cause of dandruff. While this species does occur naturally on the skin surface of both healthy people and those with dandruff, in 2007 it was discovered that the responsible agent is a scalp specific fungus,  globosa, that metabolizes present in sebum by the expression of, resulting in a lipid byproduct. During dandruff, the levels of Malassezia increase by 1.5 to 2 times its normal level. Oleic acid penetrates the top layer of the epidermis, the, and evokes an inflammatory response in susceptible people which disturbs and results in erratic cleavage of stratum corneum cells.

Seborrhoeic dermatitis
In, redness and itching frequently occur around the folds of the nose and eyebrow areas, not just the scalp. Dry, thick, well-defined lesions consisting of large, silvery scales may be traced to the less common condition of scalp. Inflammation can be characterized by redness, heat, pain, swelling and can cause sensitivity.

Inflammation and extension of scaling outside the scalp exclude the diagnosis of dandruff from seborrhoeic dermatitis. However, many reports suggest a clear link between the two clinical entities - the mildest form of the clinical presentation of seborrhoeic dermatitis as dandruff, where the inflammation is minimal and remain subclinical.

Seasonal changes, stress, and immunosuppression seem to affect seborrheic dermatitis.

Mechanism
Dandruff scale is a cluster of s, which have retained a large degree of with one another and detach as such from the surface of the. A corneocyte is a protein complex that is made of tiny threads of in an organised matrix. The size and abundance of scales are heterogeneous from one site to another and over time. cells often make up part of dandruff. Their numbers are related to the severity of the clinical manifestations, which may also be influenced by seborrhea.

Treatment
Shampoos use a combination of special ingredients to control dandruff.

Antifungals
Antifungal treatments including, and  have been found to be effective. Ketoconazole appears to have a longer duration of effect. Ketoconazole is a broad spectrum antimycotic agent that is active against  and M. furfur. Of all the antifungals of the, ketoconazole has become the leading contender among treatment options because of its effectiveness in treating seborrheic dermatitis as well.

is widely used as an anti-dandruff agent in most preparations.

Coal tar
causes the skin to shed dead cells from the top layer and slows skin cell growth.

Epidemiology
Dandruff affects around half of all adults.