This article originally appeared on Reader’s digest 

When doctors chat with patients eye to eye, it’s not just about creating rapport. Certain facial traits may reveal vital clues to underlying health conditions. We asked doctors around the country to share what they look for while examining patients. The most important tip we took away: You should worry most about a change in appearance. If symptoms are new, tell your physician.

Dry, flaky skin or lips

This is a common warning sign of dehydration. It may also indicate a more serious problem that affects sweat gland function, such as hypothyroidism (marked by insufficient levels of thyroid hormone) or diabetes, says Roshini Raj, MD, assistant professor of medicine at the NYU School of Medicine and author of What the Yuck?! Other signs of hypothyroidism include feeling cold, weight gain, and fatigue. Diabetes symptoms include extreme thirst, frequent urination, and blurry vision.

Excess facial hair

Unwanted hair, particularly along the jawline, chin, and upper lip, could be a symptom of polycystic ovary syndrome, a hormone imbalance in which male hormone levels are elevated. (The condition may affect five million U.S. women of childbearing age.)

Soft, yellow spots on eyelids

Patients with these cholesterol-filled lesions, called xanthelasmata, may have a higher risk of heart disease. A 2011 Danish study of nearly 13,000 patients found that about 4 percent had the spots and that those patients were nearly 70 percent more likely to develop hardening of the arteries and almost 50 percent more likely to have a heart attack over the next few decades than patients without them.

Eye bags and puffiness

Tired-looking eyes could be a red flag for chronic allergies, which dilate blood vessels and cause them to leak. In the sensitive skin under your eyes, this creates puffiness and a dark purple-blue hue, says Dr. Raj, who is also co-founder of the skin care company TULA.

Facial asymmetry

This can be one of the first signs of stroke, says Leana Wen, MD, an emergency physician at George Washington University and coauthor of When Doctors Don’t Listen: How to Avoid Misdiagnoses and Unnecessary Tests. “Patients will often describe it like this: ‘I looked in the mirror, and my face looked different.’” You might also notice that one side of your face is numb or feel as if you can’t fully smile. Or you might have trouble speaking. If you suspect that you or a relative may have had a stroke, call 911 right away.

Discolored complexion

Even slight changes may indicate that something may be wrong. Paleness could be a sign of anemia. A yellow tone could indicate liver disease. A bluish tint in lips or nail beds could indicate heart or lung disease, says Mallika Marshall, MD, an internist and pediatrician at Massachusetts General Hospital.

Rashes and blotches

Certain digestive problems may show up on skin, says Dr. Raj. Itchy clusters of red bumps could indicate celiac disease, an autoimmune disorder in which the body reacts to gluten. A butterfly-shaped rash across the cheekbones and over the bridge of the nose can be a sign of lupus, an autoimmune disease. Allergies, eczema and rosacea, and certain infections can also trigger facial rashes.

Receding chin

Along with traits like a thick neck and a small jaw, this could be a sign of sleep apnea, a disorder in which your breathing repeatedly stops for ten seconds or more while you sleep, says Dr. Raj. If you snore loudly, get headaches first thing in the morning, or feel excessive fatigue during the day, ask about getting tested.