What is dandruff?

Chris Smith answered the question of why dandruff can keep coming back, from Saugat in Nepal...

Chris - Well first of all what actually is dandruff? It's very common. It's more common in men than women. It's more common under the age of 50 and it tends to have its peak onset after puberty kicks in and that probably happens because once you go through puberty your hormone profile changes and your hormone profile including testosterone and oestrogen levels affect the composition of the secretions that the glands in your skin and scalp put onto the skin surface; and those secretions include oils and other things and that in turn affects the composition of the microbes the so-called microbiome that lives on the skin.

And that's probably the key to this, because dandruff is flaky skin: it's dead bits of skin, which is shed all the time. But when you get dandruff what's happened is that the process by which the skin renews itself has, for some reason, speeded up. So you’re growing more skin and losing more skin and because you’re losing more skin you’re more likely to see yourself losing more skin, which is why you get these little flakes of skin.

It’s nothing to do with hygiene. It does appear to be to due to microbes because there are various conditions which are associated with it including an overgrowth of fungus. So certain fungi growing on the scalp perfectly naturally - and you often see this in young babies actually they get something called "cradle cap" - when young babies are first born you end up with a flaky skin on the top of the head and it’s probably their own microbiome first establishing itself.

You can also get dandruff if you’re prone to eczema, which is another inflammatory skin condition, or sometimes just a certain change in products like shampoos and things which can irritate the skin can cause this to happen; and then some people have got psoriasis as well and psoriasis can sometimes also cause a dandruff like phenomenon.

你能做什么呢?你可以把它with shampoos and they often have things like zinc in them. They might have selenium in them. These are things to look for in the ingredients. Things like zinc and selenium are very good because they actually affect the microbes that cause the dandruff. Also salicylic acid, the chemical relative of aspirin, can sometimes also be in these remedies and that’s very good as well. And sometimes coal tar - in the old days people used coal tar soap: smells terrible, but it works a treat! And then there’s an anti-fungus you can rub in, something called ketoconazole, which also can be used and if you do this it suppresses the fungus that causes the dandruff.

The problem is though that, if you are prone to that particular overgrowth of those yeasts and fungi that cause it, as soon as you stop the treatment then you might get it back again and this is exactly what is being referred to in the question that it does relapse if you take away the pressure caused by the shampoo. So the best thing is, if you do get this - it's nothing to do with hygiene - people with perfectly clean hair get it equivalently with people who have dirtier hair - it’s all to do with the microbes that inhabit you and therefore the best thing to do is to find a shampoo that’s working for you and keep using it as long as it makes the problem go away.

But you know it is a pretty much a modern-era thing, because we’ve all become so obsessed about hygiene these days we tend to notice it. And I think the association with it being under 50, the cynic in me says probably because, by the time you’re 50-odd, you probably don’t care, and you might have lost your hair!