Hypothyroidism, or an underactive thyroid gland, adversely affects scalp and body hair growth. Thinning of the eyebrows can be a late sign of hypothyroidism. Other symptoms of hypothyroidism include chronic fatigue, weakness, constipation, weight gain and skin dryness. Treatment of hypothyroidism with thyroid hormone replacement medication typically leads to regrowth of lost eyebrow hair.

Other drugs commonly attributed to causing madarosis are miotics, anticoagulants, anti-cholesterol drugs, antithyroid drugs, propranolol, valproic acid, boric acid, and bromocriptine.[21,99] Anticoagulants in high doses have been found to produce loss of scalp, pubic, axillary, and facial hair with loss of eyebrows after a latent period of a few weeks of treatment with dextran and heparin.[100] Propranolol can cause diffuse alopecia along with loss of eyebrows due to telogen effluvium,[101] usually after three months of therapy.[44] Loss of medial aspect of eyebrows can be seen in fetuses exposed to valproic acid.[102] Diffuse alopecia including that of eyebrows has been described due to chronic ingestion of mouthwashes containing boric acid. There was complete reversal following stopping the practice.[103] Levodopa has been noted to cause severe diffuse alopecia within three months of daily use.[104] Hair loss can occur soon after starting topical minoxidil therapy (due to detachment of club hairs following resting hairs reentering anagen), and after cessation of therapy (due to telogen effluvium).[98]

Optimal levels of estrogen help to grow full thick hair, while low estrogen levels lead to thin and stalled hair growth, which eventually leads to hair loss. Through the years, a women will go through various cycles of highs and lows in estrogen levels. Puberty is typically associated with high estrogen levels as a woman starts to cycle through menstruation. Pregnancy typically increases hormone production, but once the baby has been delivered the mother can experience a drop in estrogen levels, which can result in thinning and loss of hair. Typically, this corrects itself as the woman's body heals and hormonal regulation returns to normal.  The largest decline in estrogen levels is during menopause. Estrogen is secreted through the ovaries and adrenal glands. When a woman hits menopause, the ovaries’ estrogen production is significantly diminished, which puts an excess burden on the adrenals to produce it. However, as the adrenals are typically overburdened due to stress, symptoms of menopauses like hair loss and hot flashes occur prematurely and excessively for some. Nourishing the body and balancing stress levels will support gentle and graceful transitions.  


Eyelash hairs are usually present in two to three rows, and are short, thick, and curved in appearance. They are set obliquely, anterior to the palpebral muscle. The upper eyelashes are more numerous and curve upward, while the lower eyelashes curve down in order to avoid interlacing during eyelid closure. Eyelash cilia are unique in that they have no erector muscles. Eyelash hairs are oval in all races.[7]
Hormones don’t just affect your mood, they are also common culprits of hair loss. A hormone imbalance caused by thyroid disease, pregnancy, menopause, or hormone medication (like birth control pills) can lead to eyebrow loss. Thankfully, once you identify the source of the hormone imbalance and address the problem, your hair will likely grow back naturally.
If you’ve gotten through this list and still don’t know what’s going on, it’s time to talk to your doc. Unfortunately, madarosis–typically used to mean the loss of eyelashes, but also referring to the loss of brows–may be due to many, many things, including a number of vision and life-threatening conditions, like herpes zoster, leprosy, HIV/AIDS, trachoma, malignant eyelid tumors, discoid lupus, scleroderma, and hypothyroidism (Khong, Casson, Huilgal, Selva; Survey of Opthamology, 2006). Brow and lash loss are both indicators of underlying diseases, so yes get to your doc stat.
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Most women with pattern hair loss don't get a receding hairline or bald spot on top of the scalp as is common in men. Instead, there is visible thinning over the crown. In men and women, hairs are miniaturized because of a shortened growth cycle where the hair stays on the head for a shorter period of time. These wispy hairs, which resemble forearm hairs, do not achieve their usual length.

Hormones are cyclical. Testosterone levels in some men drop by 10 percent each decade after thirty. Women's hormone levels decline as menopause approaches and drop sharply during menopause and beyond. The cyclic nature of both our hair and hormones is one reason hair loss can increase in the short term even when you are experiencing a long-term slowdown of hair loss (and a long-term increase in hair growth) while on a treatment that controls hair loss.

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