Changing the shape, thickness and length of the eyebrow is a commonly practiced beauty technique. Some people even remove the eyebrow entirely only to replace it with a pencil-drawn mark (eyebrow pencil). As with any part of the body, repeated irritation can eventually lead to hair loss. Sometimes this is due to manual trauma, chemicals from cosmetics or even infections that arise when breaks in the skin occur. While eyebrow modification will not stop as a commonly practised beauty technique, it should at least be minimized.

Testosterone converts to DHT with the aid of the enzyme Type II 5-alpha reductase, which is held in a hair follicle's oil glands. Scientists now believe that it's not the amount of circulating testosterone that's the problem but the level of DHT binding to receptors in scalp follicles. DHT shrinks hair follicles, making it impossible for healthy hair to survive.
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]
Reduce stress. When you are stressed, your body starts shutting down processes that aren’t necessary for survival. This shutdown can occur with physical stressors, like surgery or an illness, and emotional stress, which often manifests as physical symptoms. Loss may occur up to three months after the stressful event and may take another three to grow again.[24]
There’s no doubt that estrogen and hair loss are connected, but there are certain factors that determine how much of an effect estrogen levels have on your hair. As one of the main visible measures of your health, hair growth is often one of the first areas affected when hormones are off-balance. Let’s take a look at the links between estrogen hormonal imbalance and hair loss.
Scurf refers to the scales and greasy crusts that accumulate along the hair shaft and indicates the presence of seborrhea.[26,27] Collarettes are composed of hard fibrinous scales[25,28] surrounding each individual eyelash. They travel upward along with the growth of the lashes and are indicative of staphylococcal infection. Sleeves or cylindrical dandruff comprise scales that form a cuff around the lash root and are connected with it, in contrast to greasy scales which are not connected to the lash root.[29] Sleeves indicate infestation with Demodex folliculorum.
Madarosis is a terminology that refers to loss of eyebrows or eyelashes. This clinical sign occurs in various diseases ranging from local dermatological disorders to complex systemic diseases. Madarosis can be scarring or non-scarring depending upon the etiology. Appropriate diagnosis is essential for management. Follicular unit transplantation has been found to be a useful method of treating scarring madarosis and the procedure relevant to eyebrow and eyelash reconstruction has been discussed. A useful clinical approach to madarosis has also been included for bedside diagnosis. The literature search was conducted with Pubmed, Medline, and Google scholar using the keywords madarosis, eyebrow loss, and eyelash loss for articles from 1960 to September 2011. Relevant material was also searched in textbooks and used wherever appropriate. 
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