Hair loss is a big worry to many people, both male and female. If you have a worrying amount of hair in the basin after shampooing, you may think you are on the way to baldness, but this is not usually the case. The 50–100 hairs that everyone loses each day often become tangled with the rest of the hair but are washed out when we shampoo. So, we see what seems like a lot of hair in the basin after shampooing, but in reality these hairs have been shed earlier.
Of course, bald areas are an obvious sign of hair loss, but otherwise it can be difficult to tell whether your hair is getting thinner. To find out, try the tug test. Hold a small bunch of hair – about 15 or 20 hairs – between the thumb and index finger. Pull slowly and firmly. If more than six hairs come out there may be a problem. Increased visibility of the scalp and a receding hairline are also more objective measures of hair loss. More hair on the pillow or on clothing than usual is normally also an indicator of telogen effluvium.

How Hair Grows

The portion of the hair that we can see is called the shaft. Each shaft of hair protrudes from its follicle, which is a tube-like pouch just below the surface of the skin. The hair is attached to the base of the follicle by the hair root, which is where the hair actually grows and where it is nourished by tiny blood vessels.

Like the rest of the body, hairs are made of cells. As new cells form at its root, the hair is gradually pushed further and further out of the follicle. The cells at the base of each hair are close to the blood supply and are living. As they get pushed further away from the base of the follicle, they no longer have any nourishment and so they die. As they die, they are transformed into a hard protein called keratin. So, each hair we see above the skin is dead protein. It is the follicle, which lies deep in the skin, that is the essential growing part of the hair.

The thickness of each hair depends on the size of the follicle from which it is growing. At puberty in boys, hormones increase the size of the follicles on the chin, chest and limbs so that each hair becomes more thick and wiry. In the elderly, the follicles shrink and the hair becomes finer.

Stages of Hair Growth

Hair growth is not a continuous process. It has several stages, i.e. the growth phase (anagen), the regression phase (catagen), and the resting phase (telogen).

  • The first phase is the growing stage. Hair grows at about 1 cm each month, and this phase lasts for anything between 2 and 5 years.
  • This is followed by a resting stage, during which there is no growth. This phase lasts about 5 months and is called telogen.
  • At the end of the resting phase, the hair is shed, and the follicle starts to grow a new one.
  • At any moment, about 90% of the hair follicles of the scalp are growing hairs in the first phase; only about 10% are in the resting phase.
  • If a follicle is destroyed for any reason, no new hair will grow from it.

What Happens to Cause Baldness

Excessive hair loss can occur if any of the stages of hair growth become disrupted. For example, if follicles shut down (meaning that they stay in the resting phase and then shed the hair) instead of growing new hairs, there will be less hair on the head. Another reason might be interference with the formation of new hair cells at the root during the growing phase; this occurs with some anticancer drugs. If follicles have been destroyed (as they might be by, for example, a burn or by some skin diseases), there will be baldness in that area.
By far the most common cause for baldness, however, is ‘pattern loss’, also called androgenic alopecia. In this type of hair loss, hair on the anterior hair line and very top of the head becomes tiny and ‘miniaturised’, giving the appearance of baldness. We will focus mainly on this type of hair loss.

Scientists have discovered two genes that may increase the risk of early baldness in men. One is known as the androgen receptor gene, inherited from the mother and already linked to male pattern baldness. The other is on chromosome 20 and can be inherited from both mother and father. 14% of men carry both genetic variants (Nature Genetics 2008;40:1270–1271).

Common Beliefs about Hair Loss – True or False?

Some hairstyles can cause hair loss
True. Styles that put tension on the hairs – such as tight ponytails, plaits or corn-rows – can cause hair loss. Winding hair tightly onto rollers (particularly heated rollers) can have the same damaging effect. This is referred to as traction alopecia.

Hair extensions can cause hair loss
True, if not done properly. If the hair extensions are too tight, they can pull on the hairs and cause bald patches (which in severe cases could be permanent). However, even if done properly they can cause hair loss (traction alopecia).

Brushing the hair 100 times a day will stimulate the circulation and prevent hair loss
False. Vigorous brushing is more likely to injure the hairs and make the problem worse.

Hair needs to breathe, so wigs and toupees worsen loss of hair
False. Hair does not need to breathe. Only the root of the hair is alive, and this gets its oxygen from the blood in the scalp. Wigs and hairpieces will damage hair only if they are too tight, too heavy, or pulling on hairs. Also, adhesives are often used on the anterior hair line, so hair can be lost that way, too.

Frequent shampooing makes hair fall out
False. Shampooing simply gets rid of the hairs that have already fallen out.

Blow-drying and heated brushes can worsen hair loss
True. The reason is that extreme heat damages the proteins in the hairs, making them fragile and liable to break off. Brushing the hair during blow-drying causes more damage. Careless use of heated brushes or heated hair straighteners can even burn the scalp, so that the hair follicles are permanently damaged in that area.

Protein-containing conditioners and shampoos nourish the hair and help it to grow
False. Protein-containing conditioners only temporarily fill in defects on the surface of the hair shaft, making it smoother and thicker.

Hair dyes, perms and hairsprays worsen hair loss
False. Hair dyes, perms and hairsprays do not affect thinning hair. Perms and hairsprays can help to disguise the problem. However, any repeated action such as these can cause hair breakage.

If your father has a full head of hair, you will not go bald
False. A tendency to baldness is inherited and probably involves a combination of genes. So you are not automatically in the clear even if your father has a full head of hair. It is not true, as sometimes claimed, that only genes from the mother’s side are involved.

Baldness means that you are more likely to have a heart attack
True to some extent. A study has found that men who had lost hair at the crown of the head had a 40% increased chance of coronary heart disease. Hair loss at the front of the head (a receding hairline) increased the risk by 28% (American Journal of Epidemiology 2008;167:676–683). So if you have male pattern baldness you should stop smoking, eat healthily, have your blood pressure checked and do some exercise.

Low levels of zinc in the body are a reason for hair loss
Zinc deficiency is a well-documented cause of hair loss. The role of supplementation is move controversial (Dermatology and Therapy (Heidelb) 2019;9:51–70).

Stress can cause hair loss
True. Scientists have now identified some chemicals (including nerve growth factor, substance P, catecholamines, glucocorticoids and prolactin) that are produced in the body during periods of stress and which can affect hair growth (Journal of Investigative Dermatology 2004;123:455–457).

It is normal to lose hair from our early 30s
True. A person aged 20–30 years typically has 615 hair follicles per square centimetre. The number falls to 485 by 50 years of age and to 435 at 80–90 years of age. Also each hair is thinner. So, with ageing, hair becomes both finer and sparser.

Fascinating Facts

  • We each have about 100,000 hairs on the scalp
  • It is normal to lose 50–100 hairs from the head each day
  • Each hair on the head grows for about 5 years before being shed
  • Eyebrow hairs grow for only 10 weeks
  • Scalp hair grows at a rate of about 1 cm (just under half an inch) a month
  • A survey has shown that about 7.9 million men and 1.6 million women in the UK have hair loss problems (British Journal of Dermatology 2010;162:843–847).
  • Each year, American men spend about $900 million on efforts to regrow hair


First published on:
Reviewed and edited by: Dr Ahmed Kazmi
Last updated: October 2020

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