Many people consider eyebrows to be a frame for the face, but ... wait, did my frame just fall off the wall?

If you’re suddenly getting much more familiar— and heavy-handed — with your eyebrow pencil, it might be because your eyebrows are starting to thin out. The reasons can be any combination of age, genetics, lifestyle and perhaps even some worrying health conditions.

Are you concerned about whether your thinning is “regular” or something to take more seriously? We asked the pros to explain this phenomenon.

Dr. Claire Wolinsky, a dermatologist, said declining hormone levels (for both men and women) are often the reason for thinning brows. “With age, both testosterone and estrogen decline, which has an impact on the hair growth cycle and the hair follicle itself,” she said. “The hair follicle thins, and some stop producing entirely.”

Makeup artist Natalie Dresher noted that some lifestyle habits might also contribute to the problem. “Clogging eyebrow hair follicles with products such as SPF and moisturizer also helps speed up the thinning process,” she said. Another root cause might be how much time you spent plucking your brows over the years. “I often hear, ‘I over-tweezed my brows when I was young,’ and it’s a huge factor,” said makeup artist Denika Bedrossian.

“Eyebrow thinning can start as early as the 30s or 40s, but it tends to become more noticeable in the 50s and beyond,” said makeup artist Tarryn Feldman. “The exact age can vary widely depending on genetics, overall health and lifestyle factors.”

While thinning is an issue for many people, some have the opposite problem as they get older. We all know that grandfatherly guy whose brows get fuller every year, like Eugene Levy or Martin Scorsese. Dr. Trisha Khanna explained why: “In some people, mainly older men, some hair follicles may become more sensitive to hormones, including androgens.”

“This can result in thicker eyebrows, nose hairs and ear hairs,” the dermatologist said. Androgen hormones are the ones that contribute to male sex characteristics, reproductive health and body development.

Another observation on the luxuriantly browed comes from Dr. Abrahem Kazemi. “Sometimes these older gentlemen may not ever have groomed, plucked, tweezed or waxed their eyebrows, and therefore developed thick, long eyebrows,” the dermatologist said.

Whenever your body experiences a sudden change, it’s a good idea to talk with your doctor, and rapidly thinning brows are no exception. Dr. Janiene Luke, a dermatologist and clinical professor in the Loma Linda University department of dermatology, said: “It’s important to have eyebrow thinning or other symptoms evaluated by a dermatologist to get a definitive diagnosis.”

Even though we all tend to have less hair in general as we age, dermatologist and Mohs surgeon Dr. Michelle Henry said that if your brows are thinning dramatically, there could be underlying disease. “One key reason can be hypothyroidism, a condition where the thyroid gland doesn’t produce enough thyroid hormones,” she said. “Other possible issues include nutritional deficiencies, alopecia, eczema or severe dermatitis.”

Kazemi had this suggestion: “Make sure your vitamin D and thyroid hormone levels are within normal limits by getting an annual blood test from your primary care physician or dermatologist. Also, make sure you’re taking a multivitamin and eating a well-balanced diet.”

Eyebrow growth serums are a popular product these days, but there are documented side effects from ingredients like bimatoprost (Latisse), which is closely related to the prostaglandin family of hormones. Side effects can include redness, itchy eyes, eyelid discoloration, eyelid drooping and more.

Other serums contain minoxidil (Rogaine), a vasodilator drug that treats hair loss and high blood pressure. Side effects can include skin irritation, unwanted hair growth if the solution spreads to other parts of the face and decreased visual acuity if it gets in the eyes.

If you’d like to try an eyebrow growth serum, shop carefully to select a product that’s right for your skin type, and make sure to follow its directions. Eyebrow stylist Joey Healy suggested some serum shopping tips. “Avoid those that contain hormones, which can have some wacky side effects like irritation, dry or puffy eyes, dark under-eye circles and darkening of the eyelid,” he said. “You want to avoid those hormones that are commonly listed as prostaglandins. Instead, stick with serums that contain peptides.”

For many, though, the serums are effective and problem-free. “In my opinion, serums really work,” Feldman said. “So do castor oil and massaging the area. But first, make sure you put down the tweezers and let them grow out.”

Makeup artist Jessica Candage has a two-step approach. “Have a solid growth routine at night and a solid makeup routine for day,” she said. She’s seen it work for herself, as she transitioned from overly plucked brows in her teens to ones that she was able to “bring back to life” in her 40s. “For night, I suggest a solid growth product like Lumify lash and brow serum [which does not contain prostaglandins] along with organic cold-pressed castor oil,” she said.

“Apply to your eyelashes too, and brush the products through each night,” she said. “You’ll see a difference in a matter of weeks.”

What to do in the meantime while you’re waiting for those products to work? Candage has this advice: “Brushing a brow gel though to fluff them up and help create some density.” Her favorites include Milk Makeup Kush fiber brow gel and Patrick Ta major brow shaping wax.”

Next, she suggested using a brow pencil to create small, hair-like strokes. “The goal is to have a natural-looking brow, and that’s why I love the Maybelline Express Brow ultra slim defining eyebrow pencil. For even finer brow strokes, try the NYX Lift & Snatch eyebrow tint pen. These two products will have you looking like Brooke Shields in no time.”

Healy suggested using powder to fill in the brow. “It works by creating a shadow on the skin behind the brow, and it’s a very realistic way to add a little bit of density,” he said. If you’re considering tinting or dying the brows, he suggested consulting a professional. “It helps every hair come forward, even the peach fuzz behind the brows,” he said, adding that most people will want brows that are one shade lighter than their hair color.

Another possible option is brow lamination, suggested makeup artist Nina Soriano. “It’s always a wonderful treatment that is nonpermanent, unlike microblading,” she said, referring to the semi-permanent cosmetic tattooing technique that uses a blade-shaped tool with tiny needles to create the appearance of fuller, more defined eyebrows. “With lamination, you can relax the brow and position it upward to give a fuller and thicker appearance. Pair this with a good brow pencil-powder combo and you’ll have fuller-looking brows.”

Dr. Regine J. Mathieu offered a warning about some popular treatments. “I would caution against eyebrow tattooing or microblading, because I have so many patients who are unhappy with the results,” the dermatologist said. “Remember that laser removal of tattoos can be a lengthy and painful process.”

“Taking care of your brows and seeing a true eyebrow specialist is imperative for the health and thickness of your eyebrows,” Dresher said. “While genetics and natural aging can’t be controlled, we can absolutely camouflage hair loss in the eyebrow area with many stellar products, treatments and techniques.”