What causes hair loss

Hair shedding in androgenic alopecia is speeded up by three forces: advancing age, an inherited trait to bald early, and an over-abundance of the male hormone dihydrotestosterone (DHT) within the hair follicle. DHT is a highly active form of testosterone primary contributing factor in male pattern baldness.        

The conversion from testosterone to DHT is driven by an enzyme called 5-alpha reductase, which is produced in the prostate, various adrenal glands, and the scalp. Over time, the action of DHT causes the hair follicle to degrade and shortens the anagen phase. That means follicles will simply shrink to the size they were when you were born which produce weaker hairs. As the hair shafts become smaller, the gland continues to pump out about the same amount of oil. So as your hair thins, you will notice that your hair becomes flatter and oilier. With a steadily shorter anagen growing cycle, more hairs are shed, the hairs becoming thinner and thinner until they are too fine to survive daily wear and tear.


It is most commonly found in people with ponytails, tight braids or any hairstyles that typically pull on hair with excessive force. In addition, rigorous brushing, heat styling and rough scalp massage can damage the cuticle, the hard outer casing of the hair. This causes individual strands to become weak and break off, reducing overall hair volume.


This is the loss of hair caused by compulsive pulling and bending of the hairs. Due to the constant extraction of the hair roots, permanent hair loss can occur. Onset of this disorder tends to begin around the onset of puberty and usually continues through adulthood.


This is autoimmune disorder also known as “spot baldness” that can result in hair loss ranging from just one location (Alopecia areata monolocularis) to every hair on the entire body (Alopecia areata universalis). Although thought to be caused by hair follicles becoming dormant, what triggers alopecia areata is not exactly known. In most cases the condition corrects itself, but it can also spread to the entire scalp (alopecia totalis) or to the entire body (alopecia universalis).


This is a diverse group of rare disorders that destroy the hair follicle, replace it with scar tissue, and cause permanent hair loss. The hair loss may be accompanied with severe itching, pain and burning, and progress rapidly. In other cases the hair loss is gradual, without symptoms, and is unnoticed for long periods. It is also sometimes known as scarring alopecia and can occur in otherwise healthy men and women of all ages.


An under-active thyroid and the side effects of its related medications has been found to cause hair loss, typically frontal, which is particularly associated with thinning of the outer third of the eyebrows (also seen with syphilis). Hyperthyroidism (an over-active thyroid) can also cause hair loss, though parietal rather than frontal.


Such as major surgery, poisoning, and severe stress may cause a hair loss condition known as telogen effluvium, in which a large number of hairs enter the resting phase at the same time, causing shedding and subsequent thinning hair in men and women alike. The condition also presents as a side effect of chemotherapy. While targeting dividing cancer cells, this treatment also affects hair’s growth phase with the result that almost 90% of hairs fall out soon after chemotherapy starts.


Can also be caused by several medications, including those for blood pressure problems, diabetes, heart disease and cholesterol. Any that affect the body’s hormone balance can have a pronounced effect: these include the hormone replacement therapy, steroids and some acne medications.

Factors in hair loss


The effects of male hormones on genetically susceptible hair follicles cause androgenetic alopecia. Male hormones blamed to cause hair loss are also called androgens, hence the name “androgenetic alopecia”. There are three import  ant factors involved in the hair loss process caused by androgenetic alopecia. These factors are closely related to each other.

Hair loss due to androgenetic alopecia occurs only if a person has a specific genetic code in his or her chromosomes. This code responsible for baldness is carried by a single gene or a group of genes and may be inherited from either mother or father.

A popular explanation for the inheritance of androgenetic alopecia is that a gene that is supplied by the mother and expressed in the sons who carry it. Genetic analyses of the chromosomes of patients with androgenetic hair loss have revealed that this belief was false in two respects: First, androgenetic hair loss is inherited in an autosomal dominant manner, that is, the gene responsible for hair loss can be inherited from either parent. Second, this genetic code can be expressed in both males and females; that is, both sons and daughters may have androgenetic alopecia in their future.

Another important point to note is that not everyone who carries the gene(s) responsible for androgenetic hair loss will develop baldness. To be active, the gene for baldness has to be “expressed” in the individual. The expression of a particular gene or genes depends on several factors such as hormones, age, stress level and so on. Thus, if a person does not develop male pattern baldness, the reason can be either the absence of this gene or lack of its expression.

A specific gene (or genes) responsible for androgenetic hair loss has not yet been identified. But scientists are sure that this gene (or genes) is involved in the synthesis of male hormones, the enzyme 5-alpha reductase and androgen receptors located on the hair follicles. These are found to be the three main actors involved in the process of male pattern baldness. 5-alpha reductase is the enzyme that converts testosterone (a male hormone) to a more active form, dihydrotestosterone (DHT), which binds in turn, to the androgen receptors found on hair follicles.

Hormonal hair loss

One may ask why do some people develop male pattern baldness while others do not, although all men and women have these hormones causing hair loss and their receptors in their bodies? There is not a satisfactory answer to this question. There are some speculations however, of which the most important ones are mentioned below:

  • In the balding areas of the scalp of patients with androgenetic hair loss the number of androgen receptors in a single hair follicle is higher than normal. So that with the same level of androgens in the bloodstream, a more pronounced effect of androgens (that is, hair loss) is observed, as if their levels were higher than normal.
  • In balding persons’ hair follicles sensitivity of receptors to androgens is higher than normal, thus, resulting again in a more pronounced effect of androgens (that is, hair loss) in normal levels.
  • The activity of the enzyme 5-alpha reductase is higher in the balding area, thus, converting more testosterone to dihydrotestosterone. The higher the proportion of DHT to testosterone; the faster is the hair loss process.

Stress related hair loss

  • There are several types of hair loss, some are more severe than others and some require more medical attention than others. Telogen Effluvium is one of the most common types but it is no less unwelcome to those who suffer from it. The condition is stress related and is not permanent. Rather than simply falling out, the hair first stops growing. It can then lie dormant for as long as 3 months before actually falling out. Unlike more severe types of hair loss the hair will start to grow back during the following 6 to 9 months.
  • Another stress related type of hair loss is Alopecia Areata. This occurs when white blood cells attack hair follicles. This then leads to rapid hair loss. The loss often occurs in patches but within the space of a few weeks the entire scalp can be affected. In extreme cases body hair can also fall out. The hair often grows back in time, but not always; in some cases treatment is required.
  • The most common type of stress-induced hair loss is telogen effluvium. In this type of hair loss, the hair stops growing and lies dormant, only to fall out 2 or 3 months later. Then it grows back within 6 to 9 months.
  • If you are experiencing hair thinning or baldness and you think there may be a problem then it is advisable to consult a doctor. It may be the body’s natural ageing process but if you are still young; in your teens or early twenties, or if the loss seems irregular or uneven then there could be a problem.
  • In many cases of hair loss the root of the problem is stress. Stress has always been with us, it’s not a new phenomenon, but due to increased awareness through medical advances and the way that the condition is reported in the media, we now have a better understanding of the debilitating effect it can have on people. The demands of modern life certainly don’t help and if you are concerned that stress may be the cause of your hair loss it is worth taking a good look at your lifestyle to see if there is anything you can do to manage your stress levels. (Scroll down for additional resources) Lifestyle plays a large part in our wellbeing and our hair is not impervious to this.


It should be kept in mind that even the presence of both, necessary genes and hormones, is not sufficient to cause androgenetic hair loss. The hair loss process also needs time, during which susceptible hair follicles will be exposed to male hormones. The time required for this kind of hair loss to take place varies from one individual to another. The development of male pattern baldness is dependent on a person’s genetic expression and the level of androgens in his or her blood.

Moreover, even when there is no predisposition to androgenetic hair loss, as people get older, some hairs randomly begin to shrink both in length and diameter. This process is called miniaturization. As a result, miniaturized hairs will be shed and actual follicular units decrease in number.