When is a bad hair day or a nasty breakout more than just a pain in the you know what? When your strands, skin and even nails are desperately trying to let you know there’s a bigger problem brewing. Here’s how to figure out when it’s time to put down the volumizer and concealer, and call the doctor instead.

Beauty Alert #1: Thinning, Brittle Hair

What you think it is: Too much blow-drying and flat-ironing, or a result of aging

What it could be: A protein deficiency

Because your strands are made primarily of protein, not getting enough actually interferes with hair production and slows down growth, says nutritionist Kerri Glassman. Though this issue most commonly affects vegans and vegetarians, anyone who’s not getting enough protein can start to experience hair loss. Glassman recommends eating 46 grams of lean protein like fish, chicken and beans each day for optimal hair health.

Beauty Alert #2: Freckles on Your Lips

What you think it is: Normal freckling or sun damage

What it could be: Peutz-Jeghers syndrome

Most lip freckles are normal and harmless. In some cases, however, especially when they’re purplish, they may be a symptom of Peutz-Jeghers syndrome. Peutz-Jeghers is a disorder in which the person can develop intestinal polyps and is at a higher risk of gastrointestinal growths and tumors. “The skin and GI tract come from a lot of the same stem cells,” says Anne Chapas, dermatologist and founder of Union Square Laser Dermatology in New York. “So problems with our gastrointestinal system will often show up on our skin too.” The disease is usually inherited, so if anyone in your family has had colon or intestinal cancer, consult a doctor if you see anything suspicious.

Beauty Alert #3: Dark Undereye Circles

What you think it is: Stress and sleepless nights

What it could be: Chronic allergies

“Allergies can come from a variety of sources, and people often don’t realize they’re allergic to anything,” Chapas says. “Plus most of the environmental sources are difficult to avoid so you’re constantly being exposed to them.” The undereye dark circles and puffiness are made worse by rubbing, which is exactly what you want to do when your eyes are runny or itchy. “By scratching that thin skin, you’re irritating it even more and may even cause the capillaries to leak, creating a swollen, bruise-like effect,” Chapas adds. If you think you’re battling allergies, try an antihistamine like Allegra or Zyrtec. Taking one regularly should get rid of the irritation within a couple of weeks. If you’re still noticing an issue, request an allergy skin test from your doctor.

Beauty Alert #4: Breakouts on Your Chin and Jawline

What you think it is: Adult acne, stress or that time of the month

What it could be: Polycystic ovary syndrome (PCOS)

If you’re getting deep, cystic acne on your chin or along the jawline, it could be a sign of PCOS, says Chapas. PCOS is a condition in which a woman has an imbalance of hormones that can lead to adult acne, menstrual cycle changes, ovarian cysts, infertility and other health changes. If the breakout is not mild and coinciding with your period, is painful or isn’t treatable with topical products, it’s time to consult a gynecologist. He or she may prescribe birth control pills, such as Ortho Tri-Cyclen and Yasmin, to balance hormone levels.

Beauty Alert #5: Nail Lines and Discoloration

What you think it is: Damage from nail polish or a nail injury from bumping your hand

What it could be: Skin cancer

Nails can also suffer damage from the sun’s UVA rays. “Each time you take off your nail polish, make it a habit to check for linear bands of pigmentation,” says Robert J. Friedman, dermatologic oncologist and clinical professor of dermatology at the NYU School of Medicine. The bands run from the top to the bottom of the nail and are typically tan and brown. “If they don’t grow out within a month or so, see a doctor,” Friedman warns.

Did you know a bad hair day could be a sign of a brewing health issue?

Photo: Frank Rothe/Taxi/Getty Images