The loss of eyebrow hair, a condition medically known as madarosis, is almost always a sign of an underlying issue rather than a standalone disease. Madarosis, which can be partial or complete, unilateral or bilateral, is a common symptom stemming from a wide variety of causes, including systemic illnesses, localized skin problems, physical trauma, and nutritional deficiencies. The loss of eyebrows can negatively impact a person’s self-esteem. Determining the precise reason for the hair loss is the necessary first step toward finding an effective treatment and achieving successful hair regrowth.
Hair Loss Related to Systemic Disease
Many internal health issues can manifest as eyebrow hair loss by disrupting the natural hair growth cycle. The thyroid gland is a frequent culprit, as its hormones regulate the hair follicles. Specifically, an underactive thyroid, or hypothyroidism, is commonly linked to madarosis because low levels of the hormones T3 and T4 cause hair follicles to spend more time in the resting (telogen) phase and less time in the growth (anagen) phase.
A classic sign of hypothyroidism-related hair loss is known as Hertoghe’s sign, characterized by the thinning or loss of hair primarily on the outer third of the eyebrows, nearest the temples. Conversely, an overactive thyroid, or hyperthyroidism, can also lead to diffuse hair thinning by accelerating the hair cycle. Treating the underlying thyroid condition with hormone replacement medication often balances these levels, allowing the eyebrow hair to regrow.
The immune system’s misdirected activity is another major cause of madarosis. Alopecia Areata, where the immune system directly attacks the hair follicles, can cause patchy hair loss on the brows. In cases of systemic lupus erythematosus (Lupus), inflammation can lead to skin sores, scarring, and hair loss on the face and eyebrows. Frontal fibrosing alopecia, a form of scarring alopecia that predominantly affects postmenopausal women, is also strongly associated with the loss of eyebrow hair, sometimes preceding scalp hair loss.
Localized Skin Conditions and Infections
Dermatological problems confined to the skin of the brow area can trigger inflammation that directly irritates and damages the hair follicles. Seborrheic Dermatitis, a common inflammatory condition, causes scaly, red, and sometimes itchy patches on the skin, which can involve the eyebrows. The resulting inflammation and flaking can disrupt the hair’s anchor in the follicle, leading to shedding.
Eczema, or Atopic Dermatitis, when affecting the eyebrow region, causes intense itching, redness, and irritation, which can interfere with the hair growth process. Chronic inflammation from conditions like Psoriasis causes skin cells to multiply too rapidly, forming thick, scaly plaques that can irritate the hair follicles, leading to hair loss in the affected area.
Infections represent another localized cause. Fungal infections, such as tinea capitis (ringworm), can present as scaly, inflamed patches with hair loss. Certain bacterial infections can also cause localized inflammation and pus-filled lesions around the hair shaft. Addressing the underlying skin or infectious condition with anti-inflammatory or antimicrobial treatments is necessary to resolve the hair loss.
Physical Trauma and Styling Habits
External forces and behavioral patterns that physically stress or damage the hair follicle are common causes of eyebrow loss. The repeated practice of excessive plucking, waxing, or threading pulls the hair directly from the root. Over time, this chronic stress can traumatize the follicle, leading to inflammation and, eventually, a form of permanent hair loss known as scarring alopecia.
Trichotillomania is a psychological disorder characterized by the compulsive urge to pull out one’s hair, including eyebrow hairs. The repetitive plucking behavior physically removes the hair and can cause noticeable, often irregular, patches of loss. Severe physical trauma, such as deep lacerations or burns from heat or chemicals, can also destroy the hair follicles in the brow area.
Cosmetic procedures, such as poorly executed microblading or tattooing, can also lead to scarring and permanent follicular damage if the needle penetrates too deeply into the skin. In cases of non-scarring trauma, the hair has the potential to regrow once the damaging habit or external factor is stopped.
Drug-Induced and Nutritional Causes
The introduction of certain chemicals into the body, whether through medication or diet, can interfere with the hair’s natural growth cycle. Many prescription drugs can cause hair loss as a side effect by prematurely forcing hair follicles into the resting phase. For instance, chemotherapy agents are well-known to cause widespread hair loss, including the eyebrows, by targeting rapidly dividing cells.
Other medications, such as anticoagulants (blood thinners), high doses of Vitamin A or its derivatives (retinoids), and some thyroid medications, have been documented to disrupt the hair cycle and cause hair thinning. This type of drug-induced hair loss is usually non-scarring and often reversible, with hair typically regrowing once the medication is discontinued or the dosage is adjusted.
Nutritional deficiencies are a straightforward cause of hair loss. A severe deficiency in iron, often leading to anemia, can contribute to eyebrow thinning because iron is necessary for the production of hemoglobin, which carries oxygen to the hair follicles. Similarly, deficiencies in zinc and protein malnutrition can slow hair production and contribute to thinning eyebrows.