The eyebrows consist of two areas of hair growth that are located above the eye sockets. The exact function of the eyebrows is not yet understood. It has been suggested that the eyebrows play a role in preventing sweat and water from falling onto the eyes. However, people are more concerned about the aesthetic appeal of the eyebrows than its actual function. Like the hair and hair follicles on other parts of the body, the hair in the eyebrows can also be lost due to diseases. Hair loss from eyebrows can either be partial or complete.
Hair Growth in Eyebrows
Hair growth occurs in the hair follicles that are embedded within the skin. The hair shaft that is visible above the surface of the skin is a consequence of growth in the follicles over a long period of time. The hair follicles in the skin constitute the living part of the hair. These follicles have blood and nerve supply. The hair shafts above the surface of the skin are made up of protein and dead cells. That’s the reason we can cut the hair shafts without any pain or bleeding.
Contrary to popular belief, hair growth does not occur continuously. The growth of hair occurs in multiple phases. The following are the three phases in which hair growth occurs:
- Anagen phase: The anagen phase is the active growth phase in which cellular multiplication happens at the hair follicles. The cells are pushed out to form the hair shaft.
- Catagen phase: The catagen phase is a transitional phase that follows the anagen phase. In catagen phase, the outer layer of the hair undergoes shrinkage and becomes attached to the hair root.
- Telogen phase: Telogen is a resting phase that follows the catagen phase. The hair follicle is inactive in this phase and the hair does not grow further.
The duration of the three phases of hair growth varies. Anagen phase may occur over several years and the telogen phase may occur over a period of several months. All the hair follicles are not in the same phase of hair growth at the same time. At any given time, most of the hair follicles are in the anagen phase. Only a few are in catagen and telogen phases. For this reason, even when many of the follicles are inactive, some hair is always present.
Partial and Complete Eyebrow Hair Loss
Hair loss from eyebrows can either be partial or complete. In partial hair loss, hair fall from eyebrows occurs in patches. As a result, the eyebrows become thinner and shorten abnormally. Partial hair loss may affect either one or both the eyebrows. In complete hair loss, hair is completely lost from both the eyebrows.
The pattern of hair loss in the eyebrows can give clues about the underlying cause of the hair loss, even when no other symptoms are present. Some of the conditions that cause hair loss in eyebrows specifically affect the skin and the hair follicles in the eyebrow region. In addition, conditions that affect other areas such as the skin on the scalp, forehead and face can also cause hair loss from the eyebrows.
Read more on falling hair.
Causes of Eyebrow Hair Loss
Hair loss from the eyebrows can occur due to a variety of causes that affect the skin and the hair. Some of these causes are restricted to the eyebrows. However, it may also occur due to systemic conditions that affect the skin and hair in other regions of the body.
Telogen effluvium refers to a condition in which an abnormally large number of hair follicles enter the terminal telogen phase. When these hair fall off, they are not replaced by new hair, leading to the presence of bald patches in the eyebrows. Telogen effluvium can be caused by a number of factors, such as hormonal changes associated with pregnancy and hypothyroidism, deficiency of certain nutrients, toxicity due to metals, and chronic use of certain medications. Stress is also a factor that can cause many hair follicles to enter the telogen phase prematurely.
Contact dermatitis refers to an inflammation of the skin caused by contact with some irritant or allergen. Hair follicles also get affected when the contact dermatitis is severe. Irritant and allergic contact dermatitis of the eyebrows can be caused by various cosmetic products, including hair removal creams, hair dyes, eyebrow pencils, waxes, and hair styling products for the scalp.
Alopecia areata is an autoimmune disorder in which the immune system starts attacking the hair follicles. Scalp, eyebrows, beard, and other hairy areas of the body are affected in this condition. Hair growth is impaired and patchy hair loss is seen in the affected areas. Alopecia areata usually occurs in people who suffer from other disorders of the immune system. Psychological stress and certain drugs (such as ARVs used to treat HIV infection) have also been associated with this condition.
Hair loss can also be caused by a variety of skin infections. Both fungal and bacterial skin infections can be responsible for hair loss in the affected areas of the skin. Ringworm infection is a common cause of hair loss. Fungal infection of the eyebrows is usually related to fungal infection of the scalp (technically known as tinea capitis). Both eyebrows and scalp are frequently found to be affected at the same time. Folliculitis, caused by infection with the bacteria Staphylococcus aureus, can also lead to loss of hair from the infected follicles in the eyebrows.
Trichotillomania refers to a psychological disorder in with a person manually pulls out hair during periods of stress, anxiety, boredom, depression, or frustration. It is thought to be a psychological coping mechanism, and can be a difficult habit to break. The hair on the scalp and the eyebrows are commonly targeted in this disorder.
Eyebrow modification is a common cosmetic procedure done for aesthetic purposes. Common modifications include changes in the thickness, shape, and length of the eyebrows. At times, people may even remove the eyebrows completely and replace the bald area with a mark drawn by an eyebrow pencil. Repeated irritation caused by frequent eyebrow modifications can lead to hair loss over a period of time. The chemicals used for eyebrow modifications and skin infections that result from breaks in the skin (caused by the modification procedures) may also contribute to the hair loss.
Hair loss from eyebrows may also be caused by chemotherapy and radiation therapy used for tr.eating cancer. Psoriasis of the eyebrow or forehead can also cause hair loss from eyebrows. Psychological stress can have far reaching consequences on the body and may also lead to eyebrow hair loss by contributing to some of the conditions mentioned above.