Q: What would cause eyebrow hair to fall out? Mine are thinning quickly.

A: There are many reasons that eyebrow hair fall out. Excessive plucking, rubbing eyebrows from habit, or vigorously applying eyebrow pencil can cause eyebrows to fall out. Eyebrow hair can thin with aging, just as scalp hair can.

Telogen effluvium, a temporary condition where excessive hair falls out, can affect eyebrows as well as scalp hair. This is a normal "resting" stage of hair growth that can occur periodically. It can also be precipitated by medications, stress, trauma, or medical conditions. It can be a fairly rapid type of hair loss. It is more noticeable when hair is also being lost through normal aging.

Certain medical conditions may cause loss of eyebrows. "Hertzoge's sign" is loss of hair on the outer third of the eyebrow. This is sometimes associated with low thyroid conditions (hypothyroidism) or endocrine imbalances. Alopecia areata, an autoimmune condition where a person's own antibodies attack hair follicles, can create patches of hair loss on the scalp and can affect eyebrows and other areas where hair grows. Eczema can sometimes be associated with loss of eyebrows, often from scratching. Some medications may cause loss of eyebrows and scalp hair.

If you experience rapid loss of eyebrow hair, see your doctor to determine if an underlying medical condition or medication is causing the hair loss. If the cause is simply aging, gently applying eyebrow cosmetics can help. If the cause is telogen effluvium, Eyebrow Rogaine may be helpful in diminishing hair loss.