Dandruff

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Dandruff
Other namesPityriasis capitis, pityriasis sicca [1]
Dandruff01.jpg
A microscopic image of human dandruff
Specialty Dermatology
Symptoms Itchy and flaking skin of the scalp [2] [1]
Usual onset Puberty [1]
CausesGenetic and environmental factors [1]
Diagnostic method Based on symptoms [3]
Differential diagnosis Psoriasis, dermatitis, tinea capitis [2] [1]
Medication Antifungal cream (ketoconazole), salicylic acid [2] [1]
Frequency~50% of adults [1]

Dandruff is a skin condition that mainly affects the scalp. [1] Symptoms include flaking and sometimes mild itchiness. [1] [2] It can result in social or self-esteem problems. [4] A more severe form of the condition, which includes inflammation of the skin, is known as seborrhoeic dermatitis. [1]

Contents

The cause is unclear, but believed to involve a number of genetic and environmental factors; [1] the condition may worsen in the winter. [5] It is not due to poor hygiene, [6] [7] and the underlying mechanism involves the excessive growth of skin cells. [5] Diagnosis is based on symptoms. [3]

There is no known cure for dandruff. [8] Antifungal cream, such as ketoconazole, or the keratolytic agent salicylic acid may be used to try to improve the condition. [1] [2] Dandruff affects about half of adults, with males more often affected than females. [1] In addition, people in all areas of the world are affected. [1] Onset is usually at puberty, and it becomes less common after the age of 50. [1]

Signs and symptoms

The main symptoms of dandruff are an itchy scalp and flakiness. [9] Red and greasy patches of skin and a tingly feeling on the skin are also symptoms. [10]

Causes

Dandruff with shed hair can be symptomatic of dry skin (shed skin scales and hairs on a dark wooden tabletop) Dandruff with Hair.jpg
Dandruff with shed hair can be symptomatic of dry skin (shed skin scales and hairs on a dark wooden tabletop)

The cause is unclear but believed to involve a number of genetic and environmental factors. [7]

As the skin 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 two to seven 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: [11]

  1. Skin oil, commonly referred to as sebum or sebaceous secretions [12]
  2. The metabolic by-products of skin micro-organisms (most specifically Malassezia yeasts) [13] [14] [15] [16] [17]
  3. Individual susceptibility and allergy sensitivity.

Microorganisms

Older literature cites the fungus Malassezia furfur (previously known as Pityrosporum ovale) as the cause of dandruff. While this species does occur naturally on the skin surface of people both with and without dandruff, in 2007, it was discovered that the responsible agent is a scalp specific fungus, Malassezia globosa , [18] that metabolizes triglycerides present in sebum by the expression of lipase, resulting in a lipid byproduct: oleic acid. During dandruff, the levels of Malassezia increase by 1.5 to 2 times its normal level. [5] Oleic acid penetrates the top layer of the epidermis, the stratum corneum, and evokes an inflammatory response in susceptible people which disturbs homeostasis and results in erratic cleavage of stratum corneum cells. [15]

Bacteria are also suspected to be a cause. Staphylococcus capitis was found to be 100 times more abundant on scalps affected by dandruff. [19]

For a long time, studies on dandruff predominantly focused on fungi, particularly the Malassezia species, which are major fungi colonizing the human scalp and the dominant members of the cutaneous fungal microbiome. Of the 14 known cultured species of Malassezia, the most clinically significant species are M. restricta and M. globosa. These species have been reported to be associated with skin diseases, including dandruff, seborrheic dermatitis, pityriasis dermatitis, and atopic dermatitis. [20]

However, another microorganism community composed of bacteria also inhabits the human scalp and includes facultative anaerobic bacteria, such as P. acnes, and aerobic bacteria, such as Staphylococcus. [20]

Using 454 pyrosequencing of the microbiome on scalp dandruff, Eleven bacterial phyla were detected, but most sequences were assigned to two bacterial phyla: Actinobacteria (64.9%) and Firmicutes (32.5%). Of the 123 identified genera, Propionibacterium (63.3%, Actinobacteria) and Staphylococcus (32.4%, Firmicutes) comprised more than 95% of the total sequences. A total of 99.7% of the Propionibacterium belonged to P. acne, and 94.9% of the Staphylococcus were Staphylococcus spp (including S. epidermidis, S. capitis and S. caprae). [20]

It was found that Propionibacterium decreased from 70.8% to 50.2% in the dandruff group, whereas Staphylococcus increased from 26.0% to 43.5%. Moreover, the proportion of the other low abundance bacteria increased in the dandruff group from 3.2% to 6.4%. [20]

Redundancy analysis (RDA) identified 33 genera related to severity of dandruff including Staphylococcus showed a significant positive correlation with dandruff. In contrast, only two genera (Propionibacterium and Labrys) showed a significant negative correlation with dandruff. Because Staphylococcus and Propionibacterium were the two dominant but reciprocally inhibited bacterial genera on the scalp, these results indicated that dandruff was mainly associated with the balance of these two genera. [20]

Microorganisms on the scalp, especially fungi, have been predominantly thought to be the main cause of the development of dandruff, after several studies it was observed that there was not a close association between the bacteria in genus and fungi in species. Furthermore, the relationship between bacteria and dandruff was stronger than the relationship between fungi and dandruff. [20]

Seborrhoeic dermatitis

In seborrhoeic dermatitis, 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 psoriasis. Inflammation can be characterized by redness, heat, pain or swelling, and can cause sensitivity.

Inflammation and extension of scaling outside the scalp exclude the diagnosis of dandruff from seborrhoeic dermatitis. [12] 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 remains subclinical. [21] [22]

Seasonal changes, stress, and immunosuppression seem to affect seborrheic dermatitis. [5]

Mechanism

Dandruff scale is a cluster of corneocytes, which have retained a large degree of cohesion with one another and detach as such from the surface of the stratum corneum. A corneocyte is a protein complex that is made of tiny threads of keratin in an organised matrix. [23] The size and abundance of scales are heterogeneous from one site to another and over time. Parakeratotic 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. [5]

Treatment

Ketoconazole (Nizoral) shampoo Nizoral.jpg
Ketoconazole (Nizoral) shampoo

Shampoos use a combination of special ingredients to control dandruff.

Antifungals

Antifungal treatments including piroctone olamine, ketoconazole (Sebizole), zinc pyrithione, and selenium disulfide (Selsun Blue) have been found to be effective. [9] Ketoconazole appears to have a longer duration of effect. [9] Ketoconazole is a broad-spectrum antimycotic agent that is active against Candida and M. furfur. Of all the antifungals of the imidazole class, ketoconazole has become the leading contender among treatment options because of its effectiveness in treating seborrheic dermatitis as well. [5]

Ciclopirox (topical route) may also be used as an anti-dandruff agent. [24] [25] [26] However, it is mostly sold as cream and its main use is for treating athlete's foot, jock itch, and ringworm. [27]

Other than zinc pyrithione, the most common anti-dandruff actives (outside the US) and part of many cosmetic shampoos, are piroctone olamine and climbazole. Very recent anti-dandruff shampoos use a new ester technology, propanediol caprylate.

Exfoliating agents

Coal tar causes the skin to shed dead cells from the top layer and slows skin cell growth. [28]

Salicylic acid is an approved anti-dandruff active as per the US FDA OTC drug monograph and also used in many cosmetic anti-dandruff shampoos globally.

Etymology

According to the Oxford English Dictionary , the word dandruff is first attested in 1545, [29] but is still of unknown etymology. [29]

Related Research Articles

<span class="mw-page-title-main">Dermatitis</span> Inflammatory disease of the skin

Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can vary from small to covering the entire body. Dermatitis is often called eczema, and the difference between those terms is not standardized.

<span class="mw-page-title-main">Tinea versicolor</span> Skin disease

Tinea versicolor is a condition characterized by a skin eruption on the trunk and proximal extremities. The majority of tinea versicolor is caused by the fungus Malassezia globosa, although Malassezia furfur is responsible for a small number of cases. These yeasts are normally found on the human skin and become troublesome only under certain conditions, such as a warm and humid environment, although the exact conditions that cause initiation of the disease process are poorly understood.

<span class="mw-page-title-main">Irritant diaper dermatitis</span> Medical condition

Irritant diaper dermatitis is a generic term applied to skin rash in the diaper area that are caused by various skin disorders and/or irritants.

<span class="mw-page-title-main">Seborrhoeic dermatitis</span> Skin disease

Seborrhoeic dermatitis is a long-term skin disorder. Symptoms include flaky, scaly, greasy, and occasionally itchy and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the scalp, face, and chest. It can result in social or self-esteem problems. In babies, when the scalp is primarily involved, it is called cradle cap. Seborrhoeic dermatitis of the scalp may be described in lay terms as dandruff due to the dry, flaky character of the skin. However, as dandruff may refer to any dryness or scaling of the scalp, not all dandruff is seborrhoeic dermatitis. Seborrhoeic dermatitis is sometimes inaccurately referred to as seborrhoea.

<span class="mw-page-title-main">Zinc pyrithione</span> Chemical compound

Zinc pyrithione is a coordination complex of zinc. It has fungistatic and bacteriostatic properties and is used in the treatment of seborrhoeic dermatitis and dandruff.

<span class="mw-page-title-main">Ketoconazole</span> Antifungal chemical compound

Ketoconazole, sold under the brand name Nizoral among others, is an antiandrogen, antifungal, and antiglucocorticoid medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous candidiasis, pityriasis versicolor, dandruff, and seborrheic dermatitis. Taken by mouth it is a less preferred option and only recommended for severe infections when other agents cannot be used. Other uses include treatment of excessive male-patterned hair growth in women and Cushing's syndrome.

<i>Malassezia</i> Genus of fungi

Malassezia is a genus of fungi. It is the sole genus in family Malasseziaceae, which is the only family in order Malasseziales, itself the single member of class Malasseziomycetes. Malassezia species are naturally found on the skin surfaces of many animals, including humans. In occasional opportunistic infections, some species can cause hypopigmentation or hyperpigmentation on the trunk and other locations in humans. Allergy tests for these fungi are available. It is believed French revolutionary Jean-Paul Marat suffered from a fungal infection from Malassezia restricta, which lead to his frequent bathing in a medicinal substance.

<span class="mw-page-title-main">Tinea capitis</span> Cutaneous fungal infection of the scalp

Tinea capitis is a cutaneous fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the genera Trichophyton and Microsporum that invade the hair shaft. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern, that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often boys than girls.

<span class="mw-page-title-main">Ciclopirox</span> Antifungal medication

Ciclopirox is a synthetic antifungal agent for topical dermatologic treatment of superficial mycoses. It is most useful against tinea versicolor. It is often used clinically as ciclopirox olamine, the olamine salt of ciclopirox.

<span class="mw-page-title-main">Cradle cap</span> Human medical condition

Cradle cap causes crusty or oily scaly patches on a baby's scalp. The condition is not painful or itchy, but it can cause thick white or yellow scales that are not easy to remove. Cradle cap most commonly begins sometime in the first three months but can occur in later years. Similar symptoms in older children are more likely to be dandruff than cradle cap. The rash is often prominent around the ear, the eyebrows or the eyelids. It may appear in other locations as well, where it is called infantile seborrhoeic dermatitis. Cradle cap is just a special—and more benign—case of this condition. The exact cause of cradle cap is not known. Cradle cap is not spread from person to person (contagious). It is also not caused by poor hygiene. It is not an allergy, and it is not dangerous. Cradle cap often lasts a few months. In some children, the condition can last until age 2 or 3.

Selenium disulfide, also known as selenium sulfide, is a chemical compound and medication used to treat seborrheic dermatitis, dandruff, and pityriasis versicolor. It is applied to the affected area as a lotion or shampoo. Symptoms frequently return if treatment is stopped.

<i>Malassezia furfur</i> Species of fungus

Malassezia furfur is a species of yeast that is naturally found on the skin surfaces of humans and some other mammals. It is associated with a variety of dermatological conditions caused by fungal infections, notably seborrhoeic dermatitis and tinea versicolor. As an opportunistic pathogen, it has further been associated with dandruff, malassezia folliculitis, pityriasis versicolor (alba), and malassezia intertrigo, as well as catheter-related fungemia and pneumonia in patients receiving hematopoietic transplants.

<span class="mw-page-title-main">Tinea nigra</span> Medical condition

Tinea nigra, also known as superficial phaeohyphomycosis and Tinea nigra palmaris et plantaris, is a superficial fungal infection, a type of phaeohyphomycosis rather than a tinea, that causes usually a single 1–5 cm dark brown-black, non-scaly, flat, painless patch on the palms of the hands and the soles of the feet of healthy people. There may be multiple spots. The macules occasionally extend to the fingers, toes, and nails, and may be reported on the chest, neck, or genital area. Tinea nigra infections can present with multiple macules that can be mottled or velvety in appearance, and may be oval or irregular in shape. The macules can be anywhere from a few mm to several cm in size.

Corneocytes are terminally differentiated keratinocytes and compose most of the stratum corneum, the outermost layer of the epidermis. They are regularly replaced through desquamation and renewal from lower epidermal layers and are essential for its function as a skin barrier.

<span class="mw-page-title-main">Pityriasis amiantacea</span> Medical condition

Pityriasis amiantacea is an eczematous condition of the scalp in which thick tenaciously adherent scale infiltrates and surrounds the base of a group of scalp hairs. It does not result in scarring or alopecia.

<i>Malassezia globosa</i> Species of fungus

Malassezia globosa is a species of yeast-like fungus.

<span class="mw-page-title-main">Climbazole</span> Chemical compound

Climbazole is a topical antifungal agent commonly used in the treatment of human fungal skin infections such as dandruff, seborrhoeic dermatitis and eczema. Climbazole has shown a high in vitro and in vivo efficacy against Malassezia spp. that appear to play an important role in the pathogenesis of dandruff. Its chemical structure and properties are similar to other azole fungicides such as ketoconazole, clotrimazole and miconazole.

Malassezia pachydermatis is a zoophilic yeast in the division Basidiomycota. It was first isolated in 1925 by Fred Weidman, and it was named pachydermatis after the original sample taken from an Indian rhinoceros with severe exfoliative dermatitis. Within the genus Malassezia, M. pachydermatis is most closely related to the species M. furfur. A commensal fungus, it can be found within the microflora of healthy mammals such as humans, cats and dogs, However, it is capable of acting as an opportunistic pathogen under special circumstances and has been seen to cause skin and ear infections, most often occurring in canines.

Malassezia sympodialis is a species in the genus Malassezia. It is characterized by a pronounced lipophily, unilateral, percurrent or sympodial budding and an irregular, corrugated cell wall ultrastructure. It is one of the most common species found on the skin of healthy and diseased individuals. It is considered to be part of the skin's normal human microbiota and begins to colonize the skin of humans shortly after birth. Malassezia sympodialis, often has a symbiotic or commensal relationship with its host, but it can act as a pathogen causing a number of different skin diseases, such as atopic dermatitis.

Topical antifungaldrugs are used to treat fungal infections on the skin, scalp, nails, vagina or inside the mouth. These medications come as creams, gels, lotions, ointments, powders, shampoos, tinctures and sprays. Most antifungal drugs induce fungal cell death by destroying the cell wall of the fungus. These drugs inhibit the production of ergosterol, which is a fundamental component of the fungal cell membrane and wall.

References

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