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Dandruff
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.
With dandruff, this whole process of skin renewal (or skin turnover) speeds up, so a greater number of dead cells are being shed. 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 itchy.
Dandruff is very common. According to Proctor and Gamble, it affects more than 50% of the population of the USA – 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 started to blame 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, 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 illnesses, such as Parkinson’s disease, are more likely to have dandruff.
Common beliefs – 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.
‘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.
‘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 can not ‘catch’ dandruff from someone else, such as by using his/her brush or comb.
‘Wearing a hat worsens dandruff’
Possibly true. Pityrosporum ovale yeasts thrive best when protected from sunlight. Also, wearing a hat prevents sweat from evaporating, and this may encourage the yeast. |
Getting rid of dandruff
- 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.
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When to see your doctor
You should certainly see your family doctor if your scalp is red and itchy – or if the skin is flaky around the eyebrows, round the nose or behind the ears – 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.
Useful contacts
Proctor and Gamble USA are the manufacturers of Head and Shoulders shampoo, which contains antifungal chemicals (selenium sulfide and pyrithione zinc). Their website promotes their shampoo heavily, but also has some helpful information in the ‘Scalp questions’ section.
www.headandshoulders.co.uk/faq
Johnson & Johnson, MSD, are the manufacturers of Nizoral shampoo, which contains ketoconazole. Their UK website promotes their shampoo, but also has useful information in the sections on ‘All about dandruff’ and ‘Common questions and myths’.
www.nizoral.co.uk
The American Nizoral website also has a page on African-American hair.
www.nizoral.com
National Eczema Society website has a factsheet on seborrhoeic eczema.
(Dandruff is a mild form seborrhoeic eczema.)
www.eczema.org/sebadult.pdf
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