An overview on the causes of hair damage and its severe effects on hair shaft

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Hair Shaft Damage
There are many conditions that lead to severe damage to the hair shaft, the portion of the hair projecting out of the scalp. It is also the portion of hair that is largely exposed and most affected by cosmetics and hair treatments. Most cosmetics and treatments have a weathering effect on the hair. To know what kind of damage occurs to the hair shaft it is important to understand its structure.

The hair shaft can be subdivided into three layers:

  • Cuticle
  • Cortex
  • Medulla

  • The medulla is the innermost part of the hair shaft and it is present only in large terminal hairs. As it is generally absent in most of the hair strands so the effects of cosmetics and styling are relatively insignificant on this innermost layer.

    It is responsible for the great tensile strength of the hair.

    The cortex is protected by cuticle which is composed of six to eight layers of flattened cells that overlap each other from root to the tip of the hair.

    The normal cuticle has a smooth surface that helps the light to penetrate to the cortex. But this smooth surface of the cuticle is severely damaged in weathered hair. It is caused by all sorts of inappropriate treatments. The damaged cuticle layer is not able to provide appropriate protection to the cortex which is then exposed to harmful environmental factors, like heat or pollution, leading to the formation of damaged and dull looking hair.

    As you can see the overall hair shaft structure and chemical composition is quite complex. Any damage to this complex shaft structure leads to irreplaceable defects, because of the fact that the hair shaft is a non-living portion incapable of replenishing itself.

    Common causes of hair shaft damage
    The common causes of hair damage or shaft defects are the frequent application of chemical treatments and improper use of various styling equipment. The various chemical treatments like permanent waving and curling affects the healthy hair fiber at a vigorous rate. The result of all these artificial treatments is a weathered hair which may have frayed tips, destruction of cortical cells, and has longitudinal fissures along its length.

    Besides the general weathering from routine styling, some characteristic types of hair shaft damage are seen with particular causes. A short account of some characteristic hair shaft damage presentations are described below.

    Bubble hair –a major hair shaft damage
    Bubble hair is a major hair shaft damage caused by the improper use of various styling aids. The excess use of heat during drying and styling can lead to the formation of bubble hair. Hair dryers that are operating above 175oC or curling tongs that are above 125oC and are kept in the hair for one minute or more can induce bubbles in hair fiber. The other reason for the formation of bubble hair is frequent hair treatments like frosting.

    Mechanism of bubble hair formation

    Hair damage of the bubble hair type forms due to minute air filled spaces called vacuoles. These air filled spaces or vacuoles are present in the overall hair fiber or shaft. When the hair is wet, the spaces are filled with water. Hair dryers that are operating at 175oC make the water in the hair fiber to vaporize into steam. This steam takes up a larger space than water which makes the hair expand. Consequently, the hair turns into a sponge-like structure which is called bubble hair.

    The hairs that are filled with these bubbles are weak and brittle. The overall formation of bubbles destroys the integrity of the hair fiber or shaft. The hair may be kinked, tend to break, and sometimes this may develop into localized alopecia or patchy hair loss.


    There is no treatment for bubble hair other than to stop the use of heat and chemicals. It is best to cut off the old damaged hair, and wait for new hair re-growth.

    Matting- a severe hair fiber damage
    Matting of scalp hair is a defect where the hair bends and tangles together. This vigorous bending and tangling leads to the formation of tight knots. Though the defect is rare, it is more likely to occur in long hair.

    The main reason behind this hair shaft defect is the predominant use of shampoos that contain a considerable amount of cationic surfactant. Cationic chemicals are important surfactants in hair loss shampoo but they have to be blended with other surfactants in an adequate amount to get proper results. So while taking up any shampoo it is necessary to check the label and find out the ingredients that are used in the formulation.

    Some observations in the matting of scalp hair
    Quite a few changes have been observed while examining the damaged hair under microscope. There was a marked variation in the fiber width and some strands contained longitudinal splits of a considerable length in the hair fiber. Researchers are still uncertain about the fact that whether this can also be the cause of matting of the scalp hair.

    Treatment of the hair damage
    There is no other treatment than to cut off the affected hair and wait for new hair regrowth. Matted hair is virtually impossible to detangle.

    Besides the above mentioned hair shaft defects ,there are other types of hair shaft damage the reasons for which can be both congenital and acquired, some people have naturally weak hair where the cuticle is not properly formed.

    One such hair shaft defect that is commonly encountered by dermatologists is Trichorrhexis Nodosa which is a focal defect in the hair fiber.

    All Many of these hair defects are generally due to excessive grooming. So the obvious action to avoid hair defects is to reduce the amount of hair manipulation and treat hair naturally. People are encouraged to minimize the use of hair styling treatments that involve harsh chemicals and use only suitable hair care products. These hair care products are to be selected after a brief research or consultation with a dermatologist.

    Rodney Dawber, ”Hair: Its Structure and Response to Cosmetic Preparations”, 1996, Clinics in Dermatology l14:105-112
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