Dandruff – General Information

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Dandruff particles are visible flakes of skin that have been continuously shed from the scalp. It is normal to shed some dead skin flakes as the skin is constantly renewing itself. The new cells form in the lower layers. They are gradually pushed to the surface as more new cells form beneath them. By the time they reach the surface, the cells have become flat and overlap each other like roof tiles. By then, these cells are dead and are shed from the surface all the time. They are so small that we do not notice this is happening.
One of the mechanisms by which dandruff accumulates is accelerated skin renewal. Also, the cells are shed in clumps, which are big enough to be seen with the naked eye as embarrassing flakes, especially when they land on dark clothing. The scalp may also feel slightly to very itchy.

Dandruff is very common. It affects more than 50% of the population of the USA (Journal of Clinical and Investigative Dermatology 2015;3:10) – so it is more common to have dandruff than not! It can occur at any age but is most likely in the early 20s.

Causes of Dandruff

Surprisingly, dandruff is a bit of an enigma. About 25 years ago, dermatologists noted an association with a tiny fungus, the Malassezia yeast, on the scalp. Everyone has some Malassezia yeast on their skin, particularly in the greasy areas such as the scalp and upper back. It feeds on the natural grease of the skin, from which it produces oleic acid. The oleic acid triggers increased turnover of skin cells, resulting in dandruff. So, reducing the burden as well as preventing further build-up getting rid of the yeast should improve the dandruff.

Hormones may also be involved, because dandruff usually starts after puberty and is more common in men than women. For unknown reasons, people with some neurological diseases, such as Parkinson’s disease, are more likely to have dandruff. It is also more common in people with immunodeficiencies and children with eczema.

Common Beliefs about Dandruff – True or False?

Dandruff is due to dryness of the skin
False. Dandruff is caused by a rapid turnover of cells, so more dead cells are shed from the surface. In fact, dandruff occurs in areas where the grease glands of the skin are most active, and the skin is not usually dry. However, people suffering from dandruff can go on to develop dry scalps as the normal skin barrier is affected and water can be lost more easily.

Dandruff is more common in males than in females
True. Probably because the grease glands are affected by hormones.

Dandruff is affected by the weather
Probably true. Sunlight inhibits the growth of the Malassezia yeast, and winter flares are well documented.

Dandruff results from poor hygiene
False. Dandruff is caused by rapid turnover of skin cells, probably as a reaction to the Malassezia yeast. However, dandruff sufferers do not have more of the yeast than other people – they are just more sensitive to it.

Dandruff is contagious
False. You cannot ‘catch’ common dandruff associated with Malassezia from someone else, such as by using his/her brush or comb. However, flaking scalp from other fungal conditions such as tinea capitis is contagious.

Wearing a hat worsens dandruff
Possibly true. Malassezia yeast thrives best when protected from sunlight. Also, wearing a hat prevents sweat from evaporating, and this may encourage the yeast.

Getting Rid of Dandruff

Part of the problem with dandruff is the yeast and part is the inflammatory response mounted against it. This serves as the rationale for all therapies – either reducing yeast burden or reducing inflammation.
To help with the yeast you can use selenium, zinc, azoles etc.
To help with the inflammation avoid cosmetic products, scratching, dyeing, excessive heating, use of tar- and salicylate-containing scalp products; topical steroids are often necessary and very helpful but should be used under medical supervision.

  • Hair gels and other hair products can irritate the scalp in some people. For a while, try doing without whatever you have been using, or change to a different product.
  • Do not scratch your scalp. When you shampoo, massage your scalp without scratching. Scientists have looked at hair from dandruff sufferers who scratch, using an electron microscope that magnifies 400 times. They could see fingernail marks, damaging the hair at its root.
  • If your dandruff is mild, try shampooing your hair twice a week using any shampoo labelled ‘frequent use, for dry hair’ (not an ordinary ‘antidandruff’ shampoo). This will remove the flakes that are being shed, and the moisturizer in the shampoo will protect the scalp.
  • Avoid dyeing your hair (unless you absolutely must). We all have bacteria on our scalp, some of which are beneficial. These ‘good’ bacteria prevent dandruff yeast, and hair dyes reduce their numbers.
  • If you want to try a natural remedy, boil four heaped tablespoons of dried thyme in half a litre of water (just under a pint) for 10 minutes. Let it cool and strain it through a sieve into a jar. Massage some of the liquid onto your scalp three times a week. Do not rinse it out.
  • Look for a shampoo containing tea tree oil. Research from Australia (published in the Journal of the American Academy of Dermatology in 2002) showed that a 5% tea tree oil shampoo improved dandruff by 41%, which means that, although it did not get rid of the dandruff completely, there was a noticeable improvement.
  • For more severe dandruff, you need to deal with the yeast. This means looking carefully at the small print on the antidandruff shampoo in your local pharmacy. You could start by trying a shampoo containing selenium sulfide, which has an anti-yeast effect. Wet your hair, rub the shampoo onto your scalp and rinse off. Repeat, leaving the shampoo for 3–5 minutes before rinsing off. Do not use selenium sulfide within 48 hours of applying a hair colorant or a perm lotion. Some shampoos contain zinc pyrithione, another anti-yeast chemical.
  • The most effective treatment is an anti-yeast shampoo containing ketoconazole which, in some countries, you can buy from a chemist without a doctor’s prescription. Wet your hair, rub the shampoo onto your scalp and rinse off. Repeat, leaving the shampoo for 3–5 minutes before rinsing off. Use it twice a week for 2–4 weeks to clear the dandruff, and then once every 2 weeks, using a normal shampoo in between times.
  • Antidandruff conditioners are also available.

When to See Your Doctor about Dandruff

You should certainly see your family doctor if your scalp is red and itchy, if the skin is flaky around the eyebrows, round the nose or behind the ears, if you have other skin affected other than the scalp, if you have any bubbles or blisters in the skin, if your nails or joints are affected, if several family members develop it at the same time, and if it hasn’t responded to the counter measures – because this suggests you have the more severe form called seborrhoeic dermatitis (seborrhoeic eczema). You should also see your doctor if the dandruff is very lumpy or patchy, or if you have scaly skin elsewhere, because it could be a skin disorder, such as psoriasis.

 

First published on: embarrassingproblems.com
Reviewed and edited by: Dr Ahmed Kazmi
Last updated: October 2020

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