This excellent advice is from Caroline Bellany, as published in the Daily Mail, UK, 21 June 2008.

“For most of us, the scalp is an area of skin we rarely – if ever – see. Yet it’s one of the most abused parts of the body.

Every day it comes into close contact with brushes, chemicals, dyes, bleaches, gels and sprays. And many of us blast it with the kind of high heat we’d never dream of exposing to other bits of our body.

‘The scalp has a relatively hard time,’ says Dr Christopher Rowland Payne, consultant dermatologist at The London Clinic. ‘But apart from the balls of the feet, the heels and back, it’s the thickest part of the skin.

‘The top layer – or epidermis – is of average thickness but the dermis, which is the stronger layer of skin underneath, is thicker. Whereas facial skin may measure 1mm, the skin on the scalp is about 2mm.’

Hairs grow from roots or hair follicles, which are down-growths of the epidermis. With the scalp, hairs are thick and strong. Their roots bud down through the dermis into the underlying subcutaneous fat where they can lie 4mm below the skin’s surface.

There is a rich blood supply around the hair follicles. While the number of follicles varies enormously from person to person, according to Barry Stevens of the Trichological Society, the thicker the hair shaft, the bigger the follicle.

The average follicle will produce a hair that will grow for about a year. It will rest for a month or two and then the hair will fall out. The hair follicle will then start to produce another hair.
In male pattern baldness – which can also affect the temples of women – the hair follicles of genetically susceptible people die young on exposure to the male hormone, testosterone.

There are other causes of hair loss. Some cancer chemotherapy interferes with the growing phase and therefore results in loss of 90 per cent of the scalp hair for as long as the treatment is taken.

A more common and reversible form of hair loss, which may last for a number of months, is telogen effluvium.

This can be provoked by stressful events – doctors don’t know why but it could be due to changes in blood flow – thyroid disorder or iron deficiency.

Hair follicles have their own lubrication, which comes from sebaceous glands, and too much flow results in an oily scalp.

The scalp can be washed daily without damage to it or the hair, as long as the cleansing is done gently by using the pads of the fingers rather than the fingernails.

Dermatologists have been puzzled for years as to why skin conditions such as dandruff, seborrhoeic dermatitis and psoriasis tend to be attracted to the scalp, but Dr Rowland Payne emphasises the role of increased blood flow to the area.

‘Blood vessels dilate with heat and constrict with cold,’ he explains. ‘When they dilate, blood flow increases through them.

‘Many factors increase scalp blood flow. Internal factors include stress, being overweight or eating spicy food and external factors include over-vigorous brushing of the scalp, blow drying or washing the hair in over-hot water.

‘The reason this causes dandruff is that blood carries heat and oxygen and these speed up any chemical reaction, including skin shedding of the stratum corneum, the very top layer of the epidermis.

‘Normally the shedding process takes three weeks. But when blood flow increases, the process is speeded up and the cells are ready to shed at ten days.

‘However, the intercellular glue of the epidermis – that holds the cells together – is programmed to last three weeks, so the cells, instead of shedding imperceptibly one cell at a time, are stuck together and shed reluctantly in clumps. These are dandruff scales.’

Dandruff can be controlled with medicated shampoo containing ketoconazole, zinc pyrithione or tar. Sufferers should not wash hair in very hot water and must swiftly wash the head without massaging it.

Another skin condition that affects the scalp is allergic contact dermatitis.
‘One of the most common is the black colouring in hair dye called PPD or paraphenylenediamine,’ says Dr Payne.

‘People can have nasty allergic reactions to it. The soreness, redness and scaling can be settled with steroid applications and anti-histamines but long-term treatment can often mean lifelong avoidance of skin contact with PPD.

‘This can be a massive inconvenience as it is also found in black clothing and black leather.’
Irritant contact dermatitis of the scalp can also follow the application of bleach, causing soreness and eczema, which can be soothed with topical creams.

The skin condition psoriasis, which causes large, red, scaly patches, is also attracted to the scalp area. Patients are advised to apply a coconut oil or cream gently on to their head and leave it on for four to six hours.”Excellent information and good advice as to how to keep your hair healthy.