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How does our hair grow? At any one time, 90% of hair on the scalp is actively growing, while 10% is in a resting stage, after which those hairs are shed naturally. Hair shedding of up to 100 hairs per day is quite normal. A new hair replaces each old one that is shed. Scalp hair grows about one half-inch per month. ‘Hair loss’ (alopecia) refers to excessive shedding, thinning and/or breakage of hair.
What causes hair loss? There are many causes of hair loss. Some may result in scarring of the scalp causing permanent hair loss (Scarring alopecia), whereas others do not (Non-scarring alopecia). The causes of hair loss can also be grouped according to the most common pattern they tend to produce. These include:
- Hair thinning
- Hair breakage
- Bald patches
Causes of hair thinning
This pattern of hair loss is usually associated with a smooth scalp, free of bumps or scars. Some common causes include:
- Heredity thinning (androgenetic alopecia) - In women, this condition tends to cause hair thinning which may begin as early as teenage years but may not be noticeable until many years later. In men, it can start as recession of the hairline followed by thinning of hair on the front and centre, eventually leading to baldness sparing the back and sides of the scalp. There is no cure but treatment options include topical minoxidil, certain oral medications, hair transplantation and wigs. Micro-needling treatments, platelet rich plasma (PRP) treatments and light based treatments have also been used to stimulate hair growth in this and other conditions.
- Post partum (after pregnancy) - About 3 months after delivery, women may have excessive hair loss. This can last for up to six months but usually resolves completely.
- Severe illness, high fever, major surgery
- Anaemia (iron deficiency anaemia), anorexia, crash dieting (low protein intake)
- Thyroid disease, systemic lupus erythematosus
- Medications - Some may cause temporary hair loss e.g. some anti-depressants, some oral contraceptives and high doses of vitamin A. Other medications can cause massive amounts of hair loss, like some anti-cancer drugs. The hair tends to re-grow after treatment is discontinued.
Causes of hair breakage
- Congenital - Some individuals can be born with weak hair shafts leading to hair breakage. There are a number of rare genetic defects that can lead to these conditions.
- Improper hair care: - Chemical treatments - Dyes, bleaches, relaxers, permanent waves which are left on the scalp too long and used too often or when a mixture of procedures is done. - Frequent use of harsh heating and drying implements e.g. flat irons, hair dryers, curling irons - Frequent use of hair styles that pull on hair too tight e.g. braids, weaves, ponytails. These can also lead to thinning or bald patches especially along the hair line (traction alopecia). - Shampooing and combing too often
- Hair pulling (trichotillomania) can cause hair breakage as well as bald patches. Children can develop a temporary habit of pulling their hair until it comes out or breaks at different lengths. Adults can also suffer from this condition, in which case it is usually a psychological problem.
Causes of bald patches
The causes of bald patches are many and can be subdivided into those that cause scarring and those that do not. A few examples are described below:
- Alopecia areata causes smooth bald patches on the scalp. It can also result in loss of all body hair in extreme cases. It is more common in children. Though there is no cure, a number of topical and injectable treatments, oral medication and light therapy may be used.
- Traumatic alopecia commonly occurs in infants as an area of hair loss at the back of the scalp. It is probably caused by friction and tends to resolve completely.
There are many causes of scarring alopecia. These disorders usually begin with inflammation of the hair follicle and result in scarring of the scalp. They may cause redness, pain, tenderness, itching, burning, and a variety of bumps, some containing pus. When the scalp is scarred it may appear shiny, with loss of follicular openings (hair pores) and ultimately permanent hair loss. The earlier treatment is started the better the chance of controlling the conditions. Some of these disorders include:
- Central centrifugal cicatricial alopecia (CCCA), folliculitis decalvans, dissecting cellulitis of the scalp, acne keloidalis nuchae - These conditions involve recurrent inflammation of the hair follicle and are more common in blacks. There are many different theories of what exactly causes them. Treatment options include a combination of topical and injectable steroids and topical and oral antibiotics, and other medication. Lasers and surgical treatment may be used in some cases.
- Discoid lupus erythematosus (DLE) - This condition is an autoimmune (antibodies attacking one’s own cells) disease that results in destruction of the hair follicle. It can affect the scalp as well as other areas of skin, usually on the upper body. Treatment options include steroids and anti-malarial drugs.
Fungal infection of the scalp (ringworm) - Some types of scalp ringworm cause scaling, broken hairs and little inflammation, usually resulting in non-scarring alopecia. However, other types may cause swelling, redness, tenderness and oozing and may cause scarring alopecia. Ringworm of the scalp is contagious and requires treatment with oral anti-fungal medication. Shampoos and creams can be used along with tablets.
Hair loss is a very common problem with a vast number of causes. Your dermatologist can advise you on the best treatment options based on the underlying cause. It can also be emotionally distressing to some persons and in these situations, psychological help may also be beneficial.