You may not give your tongue much thought, but chances are your doctor does. “Telling a patient to stick out their tongue is a valid way to start examining someone,” says Dr. Jordan S. Josephson, attending physician at Lenox Hill Hospital in New York City and author of Sinus Relief Now. “In fact, in Chinese medicine they believe that the tongue actually reflects all the diseases of the body.” If you have a mystery tongue problem, Josephson recommends going to see a board certified otolaryngologist (more commonly known as an ear, nose, and throat specialist).

White coating

When the tongue looks sort of white and pasty—in patches or in its entirety—it’s an indication that there’s probably some sort of infection present on the tongue, such as a bacterial overgrowth or an autoimmune-related inflammatory disease. One possible cause: Thrush, which is an overgrowth of candida (also called yeast) bacteria. Once the infection is treated with anti-fungal drugs (either topical or oral) and the infection clears up, the tongue will return to its healthy pink shade.

Too dark

A healthy tongue should have a warm, pinkish color, so when it looks dark brown or black, you need to wonder why. And chances are, the answer will be in your diet, lifestyle or your medicine cabinet. “The filiform papillae on the top of the tongue—particularly if they’re elongated—can easily take on stains or various colors from the foods, drinks, antibiotics, lozenges, etc. that you consume,” says Sol Silverman, Jr., DDS, a spokesperson for the American Dental Association. A side effect of taking bismuth medications (like Pepto Bismol) is that the tongue may turn temporarily black. And drinking a lot of coffee, smoking or chewing tobacco can stain the tongue a brownish shade. The good news is that in both cases, it’s probably just stained from food or medicine, and simply brushing your tongue a few times should help it fade back to its normal shade. While the staining may not be permanent, beware that any kind of tobacco use increases your risk of oral cancer.

Getting hairy

“The top of the tongue is covered with little projections called filiform papillae,” explains Silverman. “They’re made up of keratin—the same protein that makes up hair, but they’re not really ‘hair.’” And under normal conditions, you wouldn’t even notice them. But certain conditions can cause them to elongate, giving the tongue a “hairy” appearance. Several factors could be responsible for causing the filiform papillae to grow, including a bacterial infection, taking antibiotics, or having a very dry mouth.

Sore spots

They may be small, but canker sores or mouth ulcers (which can occur anywhere in the mouth, including the tongue) can be extremely painful. “Most things that happen in the mouth are multi-factorial,” says Silverman. And these sores are no exception. Generally, those with a genetic predisposition to getting cankers will see them crop up when other factors fall into place—such as having a cold or fever, eating an excess of citrus fruits, or biting your tongue. But keep an eye on those spots. A normal canker will heal up and vanish in a week to 10 days. Something that lasts longer and doesn’t seem to be going away could be a sign of oral cancer and should be checked out by your doctor immediately.

A bumpy surface

The filiform papillae—projections on the top of the tongue, including the taste buds—normally stick up a little bit. But occasionally one will get temporarily inflamed, red, and a bit sore. As with canker sores, as long as the area returns to normal within a time span of a few days, the inflammation is most likely harmless. “But if it turns very red or white, is painful and tender, and most importantly, doesn’t go away, it could be a sign of oral cancer,” Josephson warns.