Eyebrow loss can result from factors that impact hormone levels in the body, such as pregnancy, thyroid conditions and birth control pills, explains DERMAdoctor. It can also occur due to chemotherapy, infections, certain autoimmune disorders, skin growths and medications that have hair loss as a side effect.
When eyebrow loss is due to hormonal imbalances in the body, correcting the imbalance by addressing the underlying cause usually results in the hair growing back, according to DERMAdoctor. Examples of infections that can cause eyebrow loss include fungal infections and syphilis. Scratching due to head lice in the eyebrows can also cause eyebrow hair to fall out temporarily.
Vitiligo, lupus erythematosus and alopecia areata are some autoimmune conditions that can lead to hair loss in the eyebrow region or other areas of the body, states DERMAdoctor. Skin growths, such as moles, warts or hemangiomas, can sometimes cause eyebrow hair to thin if the hair is unable to grow through them. Surgical removal of a growth may enable the hair to grow back, although scar tissue from the procedure can inhibit hair regrowth in some cases. Certain psychiatric medications, anti-seizure drugs and anti-hypertensives may also produce eyebrow hair loss. Examples include clonidine, valproic acid, Prozac and propranolol.
Thinning eyebrows are not always the result of a medical condition, notes DERMAdoctor. Sometimes, overplucking the brows damages the hair follicles.