Hair Loss Types: Androgenetic Alopecia to Telogen Effluvium

Losing a few strands of hair is a part of the normal hair growth cycle. However, the problem arises when the number of loose hairs increases exponentially. This can happen due to aging, hormonal imbalances, nutritional deficiencies, and environmental changes.

A normal hair growth cycle consists of three phases: anagen, catagen, and telogen. The anagen phase is also known as the growth phase and lasts for years. During this phase, our hair grows actively. The catagen phase is a transitional stage of the hair growth cycle that lasts about ten days. During this phase, the hair stops growing and separates itself from the hair follicle. The telogen, or the resting phase of hair growth, can last two to three months. During this phase, the hair remains in a resting state and falls out after completing its cycle. The same hair follicle then prepares itself for new hair growth.

Several factors can interfere with this hair growth cycle and cause hair loss. Alopecia, or hair loss, is a widespread problem all around the world that primarily affects men. Men can experience hair loss in various forms. It can cause a receding hairline, thinning hair, or crown baldness.

Hair loss is categorized into several types, depending upon their causes and the resulting symptoms. In this article, you will read about the types of hair loss, their clinical presentation, and their prevalence.

Androgenetic Alopecia

Androgenetic alopecia (AGA), also known as patterned hair loss, is the most common type of hair loss. Although it can affect both men and women, AGA is more prevalent in men. AGA affects fifty percent of men once they reach their 50s, while it affects 40% of females by age 70 (Norwood, 2001). According to another estimation, AGA affects 90% of men in their lifetime (Kabir, 2013).

While AGA is known to affect older men and women, it can start at an early age. Men affected by AGA can have a receding hairline, bitemporal hair loss, and vertex thinning. In females, the AGA causes overall hair thinning, primarily affecting the crown of the head. AGA is caused by a sex hormone or androgen called dihydrotestosterone (DHT). DHT is known to gradually damage the hair follicles, causing their miniaturization until they are no longer viable for new hair production (Qi, 2014).

Alopecia Areata

Alopecia areata (AA) is a nonscarring type of hair loss that affects men and women equally. It is an autoimmune condition where the body's own immune cells start treating the normal hair follicles as harmful objects and cause their damage. It affects 2% of the population and is more common in people with a positive family history. AA can affect any part of the body but mostly affects the scalp and beard. Alopecia areata is a painless condition that can also affect children. It can cause sudden loss of hair in small patches. In some people, this form of hair loss can result in alopecia totalis (complete loss of scalp hair) or alopecia Universalis (complete loss of body hair) (Habif; 2010, Gilhar; 2012; Otberg N, 2012).

Fortunately, alopecia areata is only temporary for most people. In 80% of people affected by alopecia areata, the hair spontaneously grows back within a year (Qi, 2014).

Telogen Effluvium

Unlike androgenic alopecia or alopecia areata, where hair loss follows a specific pattern, telogen effluvium is characterized by overall hair thinning over the scalp. Telogen effluvium happens when the hair enters the telogen phase of the hair growth cycle, but the next cycle does not begin.

Telogen effluvium can either be acute or chronic, with acute cases lasting for less than six months. Several triggers can cause telogen effluvium. The triggering factor usually occurs 2 to 4 months before the hair starts falling.

The causes of telogen effluvium include the following (Habif, 2010; Otberg N, 2012):

  • Hormonal imbalances (childbirth, hypo or hyperthyroidism)
  • Nutritional (crash diets, iron deficiency, excess of vitamin A)
  • Using certain drugs (anticoagulants, beta-blockers)
  • Mental or physical stress
  • Febrile illnesses
  • Some cancers

In most people, hair growth normally starts six months after the trigger is removed. However, in a few cases, hair can take years to regrow. This type of telogen effluvium is classified as chronic, and its reasons are not well-understood.

Most cases of telogen effluvium are subclinical, so the true prevalence of this condition is hard to establish. However, it is known to affect about 2.7% of children (Nnoruka EN, 2007).

Anagen Effluvium

Anagen effluvium is the rapid hair loss caused by damaging medical treatments like chemotherapy and radiotherapy. It is characterized by diffuse hair loss that happens more quickly and dramatically than telogen effluvium. This type of hair loss can start 1 to 4 weeks after exposure to causative agents. Anagen effluvium is considered a temporary hair loss, and hair growth usually starts approximately four months after the termination of chemotherapy. However, in some cases, this condition is permanent (Habif, 2010; Otberg, 2012).


Trichotillomania is usually a temporary type of hair loss caused by excessive and chronic hair pulling. Nevertheless, if this abnormal behavior is not controlled, it can result in permanent hair loss.

Anxiety and mood disorders are the primary culprits behind this impulsive behavior, where the patient cannot control the urge to pull their hair. This condition affects 0.6% to 13% of the population and can present in both children and adults. However, it is more prevalent in women than men (Habif, 2010; Otberg, 2012).

Different psychotherapies and behavioral therapies are considered the main course of treatment for trichotillomania in adults. This condition usually resolves on its own in children (Habif, 2010).

Traction Alopecia

Traction alopecia is caused by excessive and persistent pressure from tight hairstyles like ponytails and braids. It can also result from the heat from hair styling devices like hair straighteners and rollers. The area affected by these types of hair loss depends on where the tension is applied. It is also a temporary condition that is resolved within two months after the external tension is removed. Therefore, early detection of hair loss is essential for the effective treatment of traction alopecia (Habif, 2010; Otberg, 2012).

Patients are advised to move to more relaxed hairstyles and stop using heating devices. Some scarring and swelling can also be seen in this condition, so taking antibiotics and corticosteroids can help resolve the issue (Callender, 2004).

According to one study, traction alopecia affects 1% of people in London (Child F, 1999). About 37% of women are affected by this in South Africa (Khumalo NP, 2006).

Cicatricial Alopecia

Cicatricial alopecia or scarring alopecia is an uncommon type of hair loss that causes inflammation and scarring of hair follicles. This scarring prevents hair from regrowth from the damaged follicles. It can happen quickly or progressively and can show other symptoms like swelling, itching, and rash-like white or red lesions.

It affects around 7% of patients presenting in specialist hair loss clinics (Whiting DA, 2001).

Cicatricial alopecia can take various forms, as described below.

Discoid Lupus Erythematosus

Discoid Lupus Erythematosus (DLE) is caused by an autoimmune skin disease. This skin condition causes inflamed skin sores, scars, and hair fall. It affects people of 20 to 45 years of age and is more severe in African Americans.

DLE can be treated by the following (Hordinsky, 2008; Habif, 2010):

  • Corticosteroids
  • Calcineurin inhibitors
  • Antimalarials
  • Retinoids
  • Cyclosporine
  • Hydroxychloroquine sulfate
  • Azathioprine
  • Hydroxychloroquine (Wahie, 2011).

Lichen planopilaris

Lichen planopilaris (LPP) is caused by a variant of a skin condition called lichen planus. It mainly affects the crown and parietal areas of the skull. LLP results in dry, scaly skin of the scalp and hair falling in the form of clumps. These small patches can fuse over time to make a large bald area. It is more prevalent in young women than in men.

LLP is estimated to affect 0.89% of the general population and 0.98% of clinical patients (Li, 2020).

Central Centrifugal Cicatricial Alopecia

Central Centrifugal Cicatricial Alopecia (CCCA) is also known by the names of hot-comb alopecia and follicular degeneration syndrome. CCCA is caused by scarring that primarily affects the crown and is most common in African American women and affects about 2.7% to 5.7% of women (Dlova, 2017).

CCA is believed to be caused by using hot hair styling devices and hair products containing harsh chemicals. But these are not the only causes (Olsen, 2011).

Some Other Less Common Types of Hair Loss

A few other types of hair loss that includes the following:

  • Involutional alopecia
  • Tinea Capitis
  • Folliculitis Decalvans
  • Dissecting Cellulitis of the Scalp
  • Frontal Fibrosing Alopecia
  • Loose Anagen Syndrome
  • Hypotrichosis


Hair loss can take a toll on one's mental health, no matter the reason behind it. Knowing the signs of hair loss is vital to catch the condition at an early stage. If you notice any signs that your hair is thinning, you should visit your dermatologist to diagnose the exact cause and devise an appropriate treatment plan.