– It is normal for skin cells to flake off from the scalp; this is part of the natural life-cycle of skin as outer cells eventually die, detach and are shed. These flakes are usually so small that they are not easily seen, so this regular skin cell turnover goes unnoticed. When the rate of flaking increases, and particularly when the skin cells begin to clump together into larger compound flakes, the threshold of what is considered dandruff is reached. Dandruff is not an exact term, and can range from a condition in which the skin that forms the scalp, inflamed by environmental conditions, begins to shed skin cells in larger quantities to the extreme of seborrheic dermatitis. A variety of shampoos have been created to relieve the symptoms of dandruff and to treat the causes. read more about dandruff » | resource library for hair care »
Contact dermatitis, and the inflammation that accompanies it, can be caused by sensitivity to dyes used in hair coloring, hair oils or other types of hair care products. This can increase the rate of skin cell turnover, causing a noticeable flaking in the hair and on clothing. When the shedding takes the form of larger, oily clumps of skin cells, this is probably the sign of a skin infection by one of the Malassezia species of fungi. The fungal infection metabolizes the triglycerides in the sebum, the natural skin oils produced by the scalp, producing oleic acid as a result. It is the oleic acid which causes the inflammation and promotes a reaction of increased skin shedding in the form of dandruff flakes.
Shampoos designed to help relieve dandruff conditions are formulated to normalize the skin condition, ease the itching and reduce any fungal infection. Many anti-dandruff shampoos contain zinc pyrithione (ZPT), or a similar zinc compound, to reduce sebum production – reducing the conditions in which Malassezia can thrive – and normalizing the rate of skin cell turnover. Selenium sulfide, another ingredient often found in anti-dandruff shampoos, has similar properties. An older treatment, but still in use, is to ease the inflammation and itching sensation of the scalp with coal tar. The infection can be directly treated by shampoos containing such anti-fungal ingredients as ketoconazole or hydroxypridones (under the trade name Ciclopirox).
To help the scalp recover and renew itself, some shampoos contain a mild concentration (usually about 2%) of salicylic acid to promote exfoliation of the damaged cells and bring new, healthy cells to the surface. Many anti-dandruff treatment shampoos also include botanical extracts to help comfort the skin and allow it to heal. Extract from the Australian tea tree (Melaleuca alternifolia), comfrey leaf (Symphytum officinale), calendula flower and mallow (Malva sylvestris) root extract may be found in the formulas of healing shampoos.
Whether an episode of dandruff is caused by a reaction to an irritating compound or a fungal infection, it is important to use anti-dandruff shampoo often enough to keep the hair and scalp clean and free of the agent that is causing the difficulty. It may even be necessary to alternate among several different anti-dandruff shampoos, to allow the formulas of each to provide its own benefit.