Gradual hair thinning---including your eyebrows---is a natural part of aging, advises the Mayo Clinic. Being overzealous when applying cosmetics can cause the loss as well. However, sometimes medical conditions can cause you to lose the arches over your eyes, so you should see a healthcare provider if you're experiencing loss of eyebrow hair.
Improper Cosmetic Application
Rubbing too hard when you use an eyebrow pencil or scratching or rubbing your brows vigorously can cause their loss, advises Rebecca B. Campen in "The Comprehensive Guide to Skin Care." When you use an eyebrow pencil, it's best to use light strokes and not to rub.
Too Much Plucking
Plucking your eyebrows too much can cause thin eyebrows. In extreme cases, a condition called trichotillomania can be responsible, according to WomensHealth.gov. People with this disorder have a strong urge to pull out hair, with some also plucking their eyebrows. Although this plucking gives an immediate sense of pleasure or relief, it also causes distress. Medicines and behavioral therapy can help.
Alopecia
You may lose eyebrows due to alopecia, which is an autoimmune disorder in which hair follicles become inactive, according to WomensHealth.gov. No effective treatments are available for this condition, but recovery from it is somewhat common, according to MedlinePlus. However, if you experience the condition at a young age, also have eczema or have the condition long term, you are less likely to recover.
Telogen Effluvium
Telogen effluvium may cause you to lose eyebrows as well as hair on your head. This can happen after a shock to your system, according to the American Osteopathic College of Dermatology. Common causes include crash diets with inadequate protein, major surgeries or illnesses, severe infections, high fevers, childbirth, severe psychological stress, severe chronic illness, an over- or underactive thyroid gland and a variety of medications. You are likely to notice the hair loss several weeks, or even several months, after the incident. Treatment generally is not needed for this condition, note the experts at AOCD, because the condition occurs for a limited time.
Hypothyroidism
Hypothyroidism can cause eyebrows to thin in the late stages of the condition, according to MedlinePlus. If you suffer this condition, your thyroid gland does not make enough thyroid hormone. Other symptoms can include depression, being more sensitive to cold, thin or brittle hair and fingernails, weight gain, muscle weakness, decreased taste and smell, puffy face, skin thickening and hoarseness. Lifelong therapy with medications often is needed to correct the problem, advise the experts at MedlinePlus.



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