Understanding Hair Loss

Hair loss occurs due to many possible causes related to an individual’s genetic makeup or other factors. Through this discussion, hair restoration specialist, Dr. Amiya Prasad hopes to help you better understand the causes of your hair loss, as well as your options for treatment.We can lose about 50-150 hairs per day from normal shedding, as part of the normal hair growth cycle.

The Hair Growth Cycle

On average, hair on the scalp grows about 6 inches per year. While other mammals experience predictable cycles of hair growth and shedding, humans, on the other hand, experience random growth and shedding cycles. The number of hairs lost or gained also vary.

The hair growth cycle is made up of three phases:


The Anagen phase is otherwise known as the “active phase”. During this phase, scalp hair grows rapidly (about 1 cm every month) and continues to remain active for about 2-6 years.


The Catagen phase is a transitional phase between “active” and “resting”. The growth stops and the formation of club hair begins. This phase lasts about 2-3 weeks.


During the telogen phase, the hair follicle is completely at rest and no growth occurs. It is normal to lose anywhere between 50-150 strands of hair during this phase. The telogen phase usually lasts, more or less, about three and a half months.

Causes for Hair Loss

Telogen Effluvium (Stress-induced hair loss)

Severe stress can affect normal hair growth and result in a high amount of hair entering the telogen phase all at the same time. As a result, excessive shedding can occur, which in turn can cause bald patches. This effect, however, is temporary given that the stress is properly managed.

Hormonal Imbalance

Significant changes in hormone levels can have a drastic effect on hair. For example, estrogen levels increase during pregnancy, so it is normal to have thicker hair during that time. However, during the postpartum period, estrogen levels decrease, which results in more hair going into the catagen and telogen phases. Hair loss that occurs during this time, though, is normal. Similarly, women going through menopause also experience a decrease in estrogen and progesterone levels, which can also cause a hormonal imbalance that leads to hair loss.


Some medicines for heart conditions, blood pressure, birth control, acne and depression have been known to cause temporary hair loss. Cancer treatments like chemotherapy and radiation also commonly cause hair loss.

Infection and Disease

If left unchecked, fungal and viral skin infections and serious diseases such as lupus, thyroid disease and diabetes can thin out hair or cause hair loss altogether. Proper diagnosis and medical treatment is advised immediately.

Genetics and Age

Hair loss is a genetic issue, as people with family members who suffer from hair loss are likely to have it as well. The chances of experiencing hair loss also increases with age, and this can be predicted using the Rule of Decades. According to this rule, 30% of men in their 30s will start to experience hair loss, and 40% of men in their 40s will already be experiencing hair loss. This rule changes in women — only 30% of women under the age of 50 experience hair loss, while 50% of women over the age of 50 will experience hair loss.

Other Hair Loss Syndromes

Androgenetic Alopecia / Pattern Hair Loss

Androgenetic alopecia is the scientific name for the genetic predisposition to pattern baldness in both men and women. Androgenetic alopecia is the cause of over 95% of all pattern hair loss, including baldness in men and thinning hair in women. Pattern hair loss occurs in somewhat predictable stages, and is relentlessly progressive. Usually the earlier in life pattern hair loss begins, the more advanced the pattern will ultimately become.

In male pattern baldness, the hairs on the top of the scalp have a genetic sensitivity to the male hormone testosterone (DHT). The hairs on the sides and back of the scalp do not possess this genetic trait and is usually unaffected. For this reason, hairs removed from the sides and the back of the head will maintain their genetic predisposition when transplanted and continue to grow even when moved to the top of the scalp where hair loss initially occurred.

Alopecia Areata

Alopecia areata is an immune system disorder which causes hair follicles to stop producing hairs. Sudden loss of hair in small patches on the head is a common symptom. Advanced forms of the disorder include alopecia totalis, where all hair on the head is lost, and alopecia universalis, which results in the absence of all body hair.

Traction / Scarring Alopecia

Scarring alopecia occurs when hair strands experience consistent pulling that is usually caused by wearing hair in very tight braids, corn rows or ponytails. Because of such hairstyles, the hair follicles undergo a lot of stress, which ultimately leads to damage and hair loss.

Anagen Effluvium

Anagen effluvium is the sudden loss of growing hairs as a result of chemicals or radiation. Cancer treatments such as chemotherapy and radiation therapy halt the growth phase of hair follicles, and result in the sudden shedding of hair. Some medications (i.e. diuretics, blood thinners, acne medications and birth control pills.) can also cause hair loss as a side effect.

Lichen Planopilaris

Lichen planopilaris is a rare inflammatory condition where smooth hairless patches occur on the scalp. It affects mostly young women, although it can affect men as well, and can have wide age range. These smooth patches on the scalp can grow larger and cause aggressive hair loss. Common sites for lichen planopilaris are usually seen on the sides, front, and lower back of the scalp.

Trichorrhexis nodosa

This syndrome is characterized by the development of fraying and swelling nodes on the hair shaft that cause it to easily break. This is said to occur from repeated trauma to the hair such as excessive application of hair chemicals and hair styling.


Folliculitis is the infection of the hair follicles by bacteria, fungus, or yeast and can be caused by exposure to unhygienic hot tubs and swimming pools. Folliculitis can also occur when the skin or hair follicles becomes irritated by tight clothing, chemicals, or anything that can cause blockages in the hair follicle. Infection can also occur from cuts, scrapes and wounds that directly affect the hair follicles. With so many possible causes, folliculitis is common, but can be readily treated with over-the-counter, prescription, and even common homemade remedies like white vinegar.