According to board-certified dermatologist Jessica Weiser, M.D., founder of Weiser Skin MD (New York City and Aspen, CO), the skin, hair, and nails often reflect what's happening elsewhere in the body, sometimes before other symptoms appear. "We often think of skin, hair, and nails as cosmetic, but they're also incredibly informative," says Weiser. "While most changes turn out to be benign, persistent or unexplained symptoms are worth paying attention to because they can occasionally point to something happening beneath the surface."
Here, six changes that deserve a second look, according to Weiser.
1. A breakout that comes out of nowhere
Pimples aren't always about what you're putting on your skin. In fact, “most sudden bouts of acne indicate an acute internal change," says Weiser. Hormonal fluctuations, stress, illness, sleep loss, travel, and even a change in routine can tip the body toward inflammation—and your skin is often where it first shows up.
2. Dry skin that won't quit
If your skin still feels parched despite slathering on moisturizer, dehydration may not be the whole story. A compromised skin barrier is often to blame, whether it's related to eczema, psoriasis, over-exfoliation, harsh products, or environmental stress. When that protective barrier isn't functioning properly, skin has a harder time staying quenched.
3. Dark circles, even after a good night's sleep
Being tired certainly doesn't help, but it's rarely the only reason for under-eye darkness. Thin skin can make blood vessels more visible, natural volume loss can create shadows, and seasonal allergies can worsen discoloration through inflammation and frequent rubbing, Weiser explains.
4. Redness that lingers
Temporary flushing after a workout or a hot day is completely normal. Redness that sticks around? Different story. Rosacea is one of the most common causes and can be aggravated by factors, such as alcohol, spicy food, hot beverages, and more. The key is figuring out what's triggering it before deciding how to treat it.
5. Nails that suddenly look different
Most changes aren't cause for alarm, but new or persistent changes are worth mentioning to your derm. Horizontal grooves known as Beau's lines often appear after a significant illness or period of physical stress, green discoloration may point to a bacterial infection, while "half-and-half" nails have been linked to kidney disease, notes Weiser.
6. Itching without a rash
An itch without anything visible on the skin is often innocent. If it keeps up, however, your doctor may want to evaluate for thyroid disease, kidney, or liver dysfunction, medication side effects, neurological disorders, or, more rarely, systemic illness.