Great article from Mary McCoy on the subject:
Thinning eyebrows aren’t simply the result of over-plucking. Sometimes, women experience thinning eyebrows as a result of a medical condition or the aging process. Here are our helpful tips for remedying or disguising thinning eyebrows.
Causes of thinning eyebrows
Even though heavy-handedness with a set of tweezers is a major cause of thin eyebrows, sparse hair on your brow line may not be your fault. Several conditions can contribute to the appearance of thinning eyebrows:
Nutrient deficiency. If you’re deficient in your vitamins and minerals, your whole body will start to show it. Vitamins A, E and D promote hair growth, and vitamin B mitigates bodily stress responses, which can prevent hair loss. A deficiency in any of these vitamins can cause thinning eyebrows.
Hypothyroidism. Interestingly, an under-active thyroid can cause women to lose one-third of the hair on their eyebrows.
Eczema. Although the flaky, itchy skin condition known as eczema can occur anywhere on your body, patches of eczema underneath your brows can cause hair loss throughout the eyebrow.
Alopecia Areata. Alopecia is an autoimmune disease that causes your body to attack your hair follicles, which can include hair on the eyebrow.
Medical treatments. Chemotherapy for cancer treatments can cause hair loss, including on the brow line.
Aging. Unfortunately, the aging process can cause hair loss or thinning over the entire body, including the eyebrows.
Addressing the problem
Regardless of its origin, eyebrow thinning can be quite distressing for women. Eyebrows are a major feature of your face and presentation, so it’s important to know how to address the problem effectively.
Visit your doctor. First and foremost, you need to understand the cause of your thinning brows in order to know how to address them. Your doctor can check for underlying conditions like hypothyroidism, hormonal imbalance and vitamin deficiency. Your doctor can also point you in the right direction for products that can help regrow or mask thinning hair. Visit a dermatologist for targeted advice and cosmetic options that are available to you.
Hormone replacement. If your hair loss is the result of estrogen loss with age, or thyroid stimulating hormone with hypothyroidism, hormone replacement therapy can help.
Diet and supplements. Hair loss caused by a vitamin deficiency or eczema can be addressed with a healthy diet and targeted vitamins and supplements. Make sure you’re getting plenty of vitamins A, B and D by eating leafy greens, nuts and seeds, fish, eggs and whole grains. If you have any gaps in your diet, take the necessary supplements to promote hair growth. Your doctor can give you direction about what to eat and take for support.
While you wait for your doctor’s recommendations to take effect, you can mask the problem with a high-quality eyebrow gel. Unlike eyebrow pencils that can lead to a brow that looks drawn on, an eyebrow gel enhances your eyebrow shape with a soft color and strong hold. We like Laura Mercier Eye Brow Gel, available at Nordstrom for $20. Prior to using the gel, pencil in small sections of the brow that may be entirely bare of hair. Using a pencil sparingly will prevent a brow line that’s too harsh for your face.