What is alopecia?

Alopecia, or hair loss, is characterised by a noticeable shedding, thinning or breaking of the hair. It can affect both men and women. Causes include pattern baldness, chemotherapy, stress or an underlying medical condition.

Some people experience hair loss as a mild thinning, while in others, the hair may fall out in clumps, or bald patches may develop over time. Although hair loss is often thought of as a condition of the scalp, in rare cases hair can also be lost from other areas of the body.

Treatment results vary depending on the option chosen and the type of hair loss. Options include camouflage techniques, medications or hair transplant surgery. In general, these treatments aim to slow or hide hair loss, stimulate regrowth or replace damaged hair.

Hair growth

Hair is a unique structure that comprises:

1) The hair follicle, which is the part beneath the skin that contains the stem cells that allow hair to regrow, and; 

2) The hair shaft, which is the visible part of the hair extending above the skin surface. This is mainly made up of keratin, the same family of fibrous proteins found in nails and the outer surface as the skin.   

On the average scalp, there are around 100,000 hairs that are constantly growing (anagen phase), resting (catagen phase) and shedding (telogen phase).

Most hair (85%) is in the growing or anagen phase, and grows about one centimetre each month. About 3% of the hair is in the resting or catagen phase, which lasts 3-5 years. During the shedding or telogen phase (12%), around 100 hairs are shed each day. 

Normally, there is a balance between hair loss and new hair growth, so that overall there is no difference in thickness of the hair. However, in alopecia, due to many different causes, there is an imbalance that leads to visible hair loss. 

Hair follicles and hair loss, process of hair loss, cause of hair loss.

Healthy hair cycle.

Types and causes of hair loss

There are a number of different types of hair loss and numerous different causes, some of which are not known. In general, the main hair loss features are as follows:

Pattern hair loss

Pattern hair loss is the most common type of hair loss in both men and women. As the name suggests, the hair loss follows a particular pattern. It is also called androgenetic alopecia because it tends to happen in response to male sex hormones (androgens) and genetic factors. Women also produce androgens, but in different ways, so the pattern of hair loss is different.

Male pattern baldness

Male pattern baldness usually starts with the hair receding around the temples, followed by general thinning and balding on top of the scalp. Quite often, hair remains at the sides and back of the head. Male pattern baldness runs in families and by the age of 60, most men have some degree of baldness.1

Male pattern baldness is linked to the male sex hormone dihydrotestosterone (DHT). High levels of DHT affect the follicles, causing hairs to become thinner and grow for a shorter period. As individual follicles are affected at different times, balding occurs gradually.

Certain genes for male pattern baldness are also known to be passed on from parents to their children.

Female pattern hair loss

Female pattern hair loss usually only causes thinning of hair on the top of the head. It is generally milder than male pattern baldness and more likely to occur after menopause.

Female pattern hair loss is not as well understood as male pattern hair loss, but it is also thought to be influenced by genes and androgens. This helps to explain why female pattern hair loss occurs more often after menopause, when there are less female hormones (oestrogens) present.

Hair shedding

Hair shedding occurs due to imbalances in the hair cycle.

Telogen effluvium

In telogen effluvium, the anagen to telogen ratio is reversed by a particular event, which causes up to 70% of hairs to move into the telogen phase.

About 2-3 months after the event, widespread thinning usually occurs, rather than specific bald patches. However, new hair continues to grow, so hair loss is only temporary.

This process can be triggered by a number of factors, including:

  • Emotional stress;
  • Physical stress, such as childbirth;
  • Hormonal changes, such as pregnancy;
  • Certain medications, such as anticoagulants, antidepressants, anticonvulsants and hormones;
  • Certain medical conditions, such as infection, scalp diseases, trauma, cancer or liver disease;
  • Poisoning from heavy metals, such as selenium, arsenic and thallium, and;
  • Changes in diet, particularly those involving rapid weight loss, poor nutrition, or low levels of iron or zinc.

Anagen effluvium

In contrast, anagen effluvium occurs when hair is lost during the anagen phase of active growth. This type of hair loss is generally widespread and may affect the scalp, body and face. In most cases though, hair grows back after treatment finishes.

This condition is usually triggered by chemotherapy medications, such as doxorubicin and cyclophosphamide. It can also be a side effect of other cancer treatments, such as radiotherapy.

Alopecia areata

Alopecia areata occurs when the hair stops growing and falls out from the roots. Smooth, bald patches appear suddenly, usually as circular or oval patches on the scalp. It can occur at any age, but is most common in people aged 15-30 years. Alopecia areata occurs equally in young men and women, but later in life it mainly affects women. 

Quite often, hair grows back over months or even years, although it may look grey or white for several months until normal colour returns. Sometimes a new bald patch may appear while another is growing back.

Alopecia areata is caused by an autoimmune response, meaning that the body's immune system mistakenly attacks hair roots, leading to hair loss. It is not known what triggers this response, but genetic factors are thought to play a role.

Alopecia areata, characterised by several oval-shaped bald patches located across the top and back of the scalp.

Alopecia areata.

Scarring alopecia

Scarring alopecia describes permanent hair loss that occurs when hair follicles are destroyed, usually by skin damage or an underlying medical condition.

Quite often it is unclear what triggers this destruction. However, some known causes include:

  • Trauma;
  • Severe burns;
  • Ringworm of the scalp (tinea capitis);
  • Groups of boils (carbuncles), and;
  • Certain underlying skin or connective tissue disorders, such as scleroderma, lichen planus, discoid lupus or long-term folliculitis of the scalp (folliculitis decalvans).

Risk factors

Risk factors that may increase the likelihood of developing hair loss include:

  • Stress;
  • A family history of hair loss or baldness;
  • A personal or family history of autoimmune conditions, such as vitiligo, vitamin B12 deficiency (pernicious anaemia), or an overactive thyroid gland (hyperthyroidism);
  • Styling habits that damage hair, such as tight hairstyles, hair dyes or styling irons, and;
  • Poor nutrition, particularly if it results in rapid weight loss or low levels of iron or zinc.

Signs and symptoms

As outlined above, different types of hair loss have different signs and symptoms. In general though, hair loss can be identified by one or more of the following features:

  • Receding hair around the temples, followed by balding on top of the head (men);
  • Thinning of hair on top of the head (men and women);
  • Appearance of smooth, round bald patches, usually on the scalp;
  • Widespread thinning of hair in response to factors such as stress, childbirth, rapid weight loss, certain medications or chemotherapy treatment for cancer;
  • Permanent hair loss from damage to the follicle, and;
  • Loss of hair from the entire scalp or body (rare cases only).

Methods for diagnosis

Your doctor will most likely diagnose hair loss by looking closely at your skin and gently pulling on your hair to see how many hairs fall out. You may be asked questions about the rate of hair loss and your personal or family medical history. Blood tests may done to rule out an underlying medical condition, or you may be referred to see a specialist skin doctor (dermatologist).

A dermatologist may take a hair or skin sample to help confirm the cause of hair loss. Skin may be collected by taking a scraping of the outer layer, or through minor surgery (biopsy) to remove a small section of the deeper layers.

Types of treatment

If you wish to seek treatment, a number of options aim to slow or hide hair loss, stimulate regrowth or replace damaged hair. Treating any underlying medical conditions that may be contributing to your hair loss may also help.

Although there is no cure for hair loss, your doctor may suggest one or more of the following treatment options:

Self care

To improve the general health and thickness of your hair, avoiding tight hairstyles, harsh styling products or vigorous brushing may help. A balanced diet, with plenty of protein, fruit and vegetables, may be recommended as low levels of iron, vitamin B12, folate and other nutrients can slow hair growth.

Alternatively, a hair substitute such as a toupee, wig, hairpiece or eyelash extensions may help to hide the appearance of hair loss. Other cosmetic options include lightly brushing mascara into the roots, or colouring the scalp to match existing hair. A professional trained in cosmetic procedures may also be able to bleach existing hair or tattoo the eyebrows or other areas to give the appearance of hair.

Pattern hair loss medications

The two most common medications prescribed for pattern hair loss are minoxidil and finasteride. Results vary from person to person, but these medications are not commonly known to stimulate hair regrowth. Instead, they tend to slow or decrease the progress of hair loss. Once treatment is stopped, hair loss usually continues. Minoxidil can be taken by men and women, whereas finasteride can only be taken by men.

In women only, oral hormonal medications such as spironolactone or cyproterone acetate may be prescribed. These medications have anti-androgen effects. 


Although there is no single effective treatment for alopecia areata, a course of corticosteroid injections may help speed up natural regrowth in bald patches. Options may include triamcinolone or betamethasone. Corticosteroids most likely block the autoimmune response thought to cause alopecia areata.

Injections are usually given by a dermatologist every 4-6 weeks. Several are usually given per session and then regrowth takes 1-2 months. As injections can be quite painful, this type of treatment is generally only suitable for small patches of baldness.

For the treatment of alopecia areata, your doctor may also prescribe a steroid cream for application directly onto the skin. However, corticosteroids can cause side effects, such as thinning of the skin, acne or a red rash. For this reason, they are usually only prescribed for short-term use.


In cases of alopecia areata where hair loss is widespread, your doctor may prescribe immunotherapy medication, such as diphencyprone (DPCP) or dinitrochlorobenzene (DNCB). These medications trigger a mild immune response in the skin, known as contact allergic dermatitis. This allergic reaction may result in hair regrowth over a period of about three months.

Immunotherapy is usually given weekly at specialised centres over several months. Side effects from immunotherapy may include a skin reaction, irritation or swollen lymph nodes. It is also quite common for hair to fall out again after treatment is stopped.

Another option may be an irritating skin ointment, such as dithranol. Similar to immunotherapy, irritation can stimulate hair regrowth in some people. Dithranol is applied to the scalp regularly and then washed off. Side effects may include itching, scaling or staining of the skin.

Hair transplant surgery

Transplant surgery is mainly used to treat pattern baldness in men. During this procedure, a surgeon removes ‘donor grafts’ of hair from the back and sides of the scalp and then transplants them into bald areas. Each graft contains one or more hairs still attached to a small patch of skin.

This procedure can take up to several hours and may need to be repeated a few times to achieve improved coverage of a balding scalp. Treatment results can vary from person to person.

As in most surgical procedures, additional side effects of hair transplantation may include pain, swelling, bleeding, numbness and infection. Sedative and local anaesthetic medications are administered to help prevent pain and discomfort.

Removal of a donor graft from the back of a man's head, separation of the graft into single units containing two to three hairs each and transplantation into the balding scalp.

Hair transplant surgery in men.

Potential complications

Hair loss can increase the risk of sunburn on the scalp. However, this can be avoided by wearing a hat or applying sunscreen with a high sun protection factor (SPF) when outdoors.

In rare cases, alopecia areata can progress to alopecia totalis, which describes loss of all hair from the scalp. Rarer still is alopecia universalis, which is loss of all body hair, including the beard, eyebrows and eyelashes. The earlier these conditions start, the more likely they are to be widespread. Similarly, if the condition is widespread, hair is less likely to grow back.

As hair loss affects the appearance, widespread or early shedding may lead to psychological issues such as embarrassment, social withdrawal, low self-esteem or depression.


Full recovery of hair is common when the hair loss is not long-term or widespread. Normal thickness is often achieved within months to a year in cases of telogen effluvium, anagen effluvium and alopecia areata.

However, when hair loss affects half of the scalp or more, it is much less likely that hair will regrow. Hair regrowth is also more unlikely when hair loss starts at a young age, or occurs together with nail abnormalities, allergies or an autoimmune condition.

Treatment results from taking medications vary depending on the option chosen and type of hair loss. Medications used for pattern hair loss tend to slow the progress of hair loss, rather than stimulate new growth.


In many cases, hair loss cannot be prevented, particularly if it is caused by genes, hormones, an underlying medical condition or chemotherapy. However, a diet containing healthy levels of iron, vitamin B12 and folate can help to promote steady hair growth. Similarly, avoiding tight hairstyles, harsh styling products or vigorous brushing is also recommended.

Last Reviewed: 03/10/2018

Reproduced with permission from Health&.