Pregnancy, hormone intake and other conditions affecting the body's hormonal balance; chemotherapy agents; cancer; and leprosy, syphilis, fungal infections and other infectious conditions are common causes of eyebrow loss, reports DERMAdoctor. Autoimmune disorders, inflammation resulting from skin conditions, skin growths and certain medications are also possible causes.
Chemotherapy leads to temporary hair loss, as it interferes with the creation of various cell types, explains DERMAdoctor. Cancer that grows in a localized area or spreads to other areas on the skin tends to push out existing hair, leading to a noticeable growth or a thick bump.
Patches of hair loss possibly indicate syphilis. Infections harm the hair shaft or hair follicle, and sometimes trigger inflammation that causes hair loss due to scratching.
In patients with autoimmune diseases, the body overreacts and destroys healthy tissue, causing symptoms like hair loss, according to DERMAdoctor. Patients with lupus erythematosus may experience patchy hair loss. Alopecia areata is an autoimmune disorder in which the body specifically destroys hair.
Skin diseases, such as contact dermatitis, eczema, psoriasis and seborrhea, can lead to eyebrow loss when affected individuals scratch inflamed areas incessantly, notes DERMAdoctor. Skin growths also cause hair loss, because hair is unable to grow through the thick obstructions. Scars, sclerosing disorders and other infiltrating disorders cause hair loss by interfering with the hair follicles' ability to grow.