J. K. Rivers, MD, FRCPC
Department of Dermatology and Skin Science, University of British Columbia,
Vancouver, BC, Canada
Each part of the body requires specific care, and without exception, hair has its
own unique needs that demand special attention. The most noticeable and densest
hair on the human body is on the head, where, on average, there are approximately
100,000 hairs that typically grow at a rate of 12mm/month. The self-perceived
state of an individual’s hair, especially in women, can contribute to heightened
social distress, self-consciousness, and lower self-esteem. Consequently, for many
people, the management of head hair can cause ongoing frustration and the drive
to achieve the perfect head of hair often becomes an elusive pursuit; for some this
can evolve into a disruptive preoccupation. A simple common sense approach is
recommended for promoting and maintaining healthy hair. Apart from getting
a cut or re-style, basic modifications in hair care can be easily implemented to
achieve desirable effects.
Hair is mostly made up of keratin, which is also found in the skin and nails. Each
strand of hair is comprised of three distinct layers:
- Cuticle – the outermost protective layer of the hair shaft.
- Cortex – mainly composed of keratin, this layer gives the hair its strength, color, shape, elasticity, and texture.
- Medulla – the innermost or core layer is usually only present in coarse hair, and absent in fine strands.
Although there are no biochemical differences in the hair of people from different
backgrounds, there are structural variations. For example:
- Asians tend to have straight hair with the largest mean cross-sectional areas and hair follicles that are round.
- Caucasians have intermediate mean cross-sectional areas and oval shaped hair follicles.
- People of African descent have hair that is spiraled with the smallest crosssectional areas and follicles that are elliptical.
- Hair tends to be kinky and usually does not need to be shampooed as often as straight hair.
- The removal of natural oils can leave the hair dull and difficult to style.
- In general, their hair is more fragile; its spiral structure makes it more difficult for the sebum to easily coat the hair shaft, producing drier and less manageable hair.
Hair Growth Cycle
Hair follicles grow in repetitive cycles, which include three phases:
- Anagen – growth phase, which typically continues for 150 weeks on the scalp.
- Catagen – transitional phase, during which time, the bulbar portion of the follicle is almost completely degraded through apoptosis. Catagen lasts for 1 week.
- Telogen – resting phase, lasts for 12 weeks on the scalp. Approximately 50-100 telogen hairs are shed daily, mostly because of normal washing and combing.
- Shampooing regularly is the first step in maintaining healthy hair and scalp.
- Sebum lubricates and protects hair, but particles of dirt become embedded in the oil.
- Shampooing too frequently can cause extensive sebum removal, which results in dull looking, static-prone hair that is difficult to comb.
- Shampoos consist primarily of:
- contain both hydrophobic ingredients, those attracted to oil, and hydrophilic ingredients, those attracted to water.
- allow shampoo to bind to and emulsify dirt, sebum and styling products in the hair, and then remove them when rinsing.
- responsible for lubricating the hair, allowing for easier brushing and a smoother look and feel to the hair when dried.
- cationic polymers
- provide unique wet-conditioning and delivery benefits.
- allow many consumers to forego a separate conditioner if their hair is already in good condition.
- cationic polymers
- contains preservatives, perfumes, and sometimes dyes and anti-dandruff ingredients.
- Added ingredients such as vitamins B and E, jojoba and aloe vera claim to strengthen hair, but there is no scientific validation.
- An endless array of formulations are available, and selecting an appropriate product can be confusing. A good place to start is to determine suitability by hair type, e.g., normal or dry.
- Other types of shampoo include:
- products designed for chemically treated or damaged air.
- mild infant formulations that do not irritate the eyes and exclude perfumes
- those with added medical ingredients
- conditioning shampoos that contain hydrolyzed proteins designed to penetrate the hair shaft
- professional-grade cationic acidic shampoos that neutralize the residual alkalinity of chemical treatments.
- Conditioners efficiently restore moisture that has been removed through washing.
- They contain many of the same ingredients that are found in shampoos, but in different concentrations.
- They effectively flatten the cuticle on the hair shaft and detangle the hair, which:
- makes brushing easier.
- creates smoother texture.
- improves overall manageability.
- reduces static electricity by
- adding positively-charged ions on the hair shafts.
- neutralizing the negative electric charges on the shaft that are generated following brushing.
- They are particularly useful for dry or damaged hair.
- Overuse of conditioners can result in a flattened, limp or oily appearance.
- Apply only to the hair and not the scalp.
- The cationic polymers found in conditioners are attracted to the damaged cuticle in the hair shaft, which results in the protection and repair of these areas by filling in the defects.
Damage to the hair shaft can be caused by:
- vigorous towel-drying
- washing long hair too frequently (e.g., more than once per day)
- excessive combing and brushing
- chemical treatments (e.g., permanent waving, bleaching, dyeing, straightening)
- over-exposure to sun and chlorine.
Anyone using heat generating devices or chemicalbased products for hair curling or straightening should be encouraged to carry out a regular conditioning regimen.
Applications that provide lubrication can somewhat reduce the damage and brittle texture that is associated with some of the chemicals that are used.
Hair frequently sustains damage from the intense heat generated by hairdryers in combination with the pulling and tugging of styling.
- Air-dry or gently towel-dry whenever possible.
- Set hairdryer at a lower temperature.
- Chemically-damaged hair is more susceptible to further damage to the hair shaft.
- Wet hair can be more easily damaged.
- Use a wide-tooth comb to gently untangle damp hair.
- When dry, particularly if the hair is fine or brittle, use of a natural bristle brush or comb will assist in spreading the oil (sebum) along the hair shaft.
- Makes the hair easier to style.
- Gives it a glossy appearance.
- Dandruff is influenced by the presence of 3 factors: sebum, Malassezia yeasts, and one’s individual susceptibility to irritation caused by the yeasts metabolic byproducts (free fatty acids).
- Primary ingredients in anti-dandruff shampoos include:
- Pyrithione zinc, ketoconazole, selenium sulfide, and cyclopyroxolamine
- believed to address the fungal cause of dandruff
- Salicylic acid and coal tar
- treat the symptoms of flakes and skin hyperproliferation.
- Pyrithione zinc-containing anti-dandruff formulations are safe for daily use.
- Patient compliance is improved with the use of a cosmetically appealing and effective product.
- Pyrithione zinc, ketoconazole, selenium sulfide, and cyclopyroxolamine
- Use of a shampoo and conditioner containing the same active ingredient can improve efficacy.
- In Canada, an anti-dandruff conditioner will become available in early 2008.
- Using a regular conditioner can reduce the dandruff shampoo’s efficacy.
- For conditioners containing anti-dandruff active ingredients, massage product into the scalp, then distribute evenly from hair root to tip.
- Avoid scratching the scalp, as this will loosen more flakes and cause further irritation.
Other Factors Influencing the Condition of Hair
- Excessive or incorrect use of chemical hair treatment processes such as dyeing, straightening, bleaching or perming can result in damage, accelerated hair loss and allergic reactions, more specifically, contact dermatitis.
- Exposure to the sun, chlorine in swimming pools, and seawater can inflict additional damage to hair and alter its color. Wearing a hat or applying special sunscreens formulated for the hair can provide some protection.
- Longer hair is particularly susceptible to additional damage due to the cumulative effects of various treatments and environmental elements.
- Drastic dietary changes can cause hair loss and retard growth through protein depletion.
- Tension on the hair shaft from styling can cause frontal shedding; heavy/tight ponytails can promote hair loss.
- During pregnancy, hair is particularly full and vibrant in appearance; however, postpartum hair loss (telogen effluvium) is commonly experienced by women for several months before returning to normal.
- Avoid shampooing prior to applying chemical hair treatments, as this will prevent removal of the natural oils or sebum, which will, to some degree, reduce the harsh effects of the agents used.
- Backcombing or teasing the hair by combing in the reverse direction can create damage to the hair shaft cuticle.
Allergic Contact Dermatitis
Symptoms of cosmetic, allergic, and contact dermatitis include swelling and inflammation on the scalp, face, neck, ears, and
hands. Some common examples of chemical allergens in hair products include:
- permanent hair waving agents such as glycerol monothioglycolate
- many additives in shampoos can be irritating to those with eczema
- metallic salts in permanent dyes; semipermanent and temporary variations tend to be less irritating to the scalp and cause less damage to the hair
- paraphenylenediamine, an ingredient in most hair dyes, commonly causes allergic contact dermatitis; owing to the high frequency of these reactions, manufacturers of at-home hair-coloring products encourage patch testing before use.
Implementing basic proper hair care is essential to maintaining healthy hair. Furthermore, minimizing exposure to chemical
agents, inadvisable grooming techniques, and prolonged exposure to environmental elements, will promote healthier hair
and avoid unnecessary hair loss.