Dandruff is a common condition, affecting up to half the adult population worldwide. Although not serious, dandruff can be embarrassing and affect wellbeing, and its recurring nature can be a source of frustration for sufferers.
Dandruff (or pityriasis capitis) is a mild form of seborrhoeic dermatitis that affects only the scalp. Symptoms include itchy, flaking skin without visible inflammation. Dandruff affects up to half of adults and tends to appear during adolescence when sebum production increases.
Seborrhoeic dermatitis is a common skin condition affecting areas of the body where there are more
sebaceous glands, such as the scalp, face and chest. Symptoms include itchy, scaly or flaking skin. Unlike dandruff, the skin may appear red and inflamed.
The Primary Factors Leading to Dandruff
Despite its high prevalence, dandruff is not well understood. However, evidence points to three main factors that, together, contribute to the development of dandruff.
- Colonisation with a yeast-like fungus called Malassezia
- Increased sebum production
- Individual susceptibility
Dandruff is not caused by poor hygiene, although flakes may be more obvious if hair is not washed regularly. It is not contagious.
Malassezia Colonisation: How Fungal Overgrowth Triggers Dandruff
Malassezia is a yeast-like fungus found mainly on the sebaceous areas of the body and forms part of the normal skin flora (microbiome).
Its role as a causative agent in dandruff was confirmed by the use of antifungal shampoos that reduced Malassezia numbers and dandruff symptoms.
Higher numbers of Malassezia on the scalp correlate with symptom severity. Malassezia feeds on human sebum, releasing metabolites that irritate and disrupt the outermost layer of the skin (the stratum corneum).
Increased Sebum Production
Dandruff incidence strongly correlates with sebaceous gland activity during the lifespan. Sebum production is under hormonal control: circulating androgens at puberty increase sebum production during adolescence, which then remains stable during the 20s and 30s, gradually declining thereafter.
Sebum secretion is greater in men and stays higher for longer. There is also some evidence that altered sebum composition may also play a role in the development of dandruff, creating a more favourable environment for Malssezia to grow.
Individual Susceptibility
Other predisposing factors may contribute to the development in some individuals.
These include:
- Altered skin barrier function
- Abnormal immune system response
- Genetic factors
- Emotional stress
- Nutritional factors, such as zinc deficiency
Dandruff vs. dry scalp
Dandruff and dry scalp have the same main symptoms of flaking skin and itch, but they are two different conditions. Dandruff flakes are generally larger as they are composed of a cluster of corneocytes (skin cells) that have become detached from the stratum corneum while adhered to one another. Flakes tend to look oily and may be yellowish in colour. People with dry scalp tend to have small, dry flakes and dry skin on other parts of their face and body
Treating dandruff
Anti-dandruff products can be divided into two main groups:
- Medicated treatments/shampoos that are used once or twice a week but do not replace normal shampooing to cleanse the hair and scalp
- Shampoos that can be used in place of a normal cosmetic shampoo
A variety of active ingredients are used in anti-dandruff products such as ketoconazole and selenium sulphide. Ketoconazole 2% is suggested for more persistent or severe dandruff. Corticosteroid gels and lotions may be used if there is severe itching of the scalp. ketoconazole is as effective as steroids in treating seborrhoeic dermatitis of the scalp and face, with 44% fewer side effects.
Keeping dandruff at bay
Its is a chronic condition that requires long-term treatment. Antifungal treatments are suppressive rather than curative so it will often recur if treatment is stopped. It is therefore important that patients continue to use the treatment shampoo, according to the manufacturer’s instructions, to prevent recurrence of symptoms. Use of a daily anti-dandruff shampoo in between the medicated treatments may also help keep symptoms at bay.
- Use a medicated shampoo with antifungal agents
- Consider ketoconazole shampoo if dandruff is persistent or more severe
- Always read labels carefully before use
- Keep using the treatment shampoo regularly, as instructed, to prevent recurrence
- Consider using a daily anti-dandruff shampoo to help keep symptoms at bay
- Consult your doctor if dandruff persists after a month, or if there are signs of infection
