Remember when the doctor used to ask you to "open wide and stick out your tongue?" He was probably checking more than your mouth and throat. Very often, your tongue can provide valuable clues about what's going on with your health. A healthy tongue is smooth and pink, but when infections, stress, or side effects of medication take their toll, a change in the appearance of your tongue could signal it's time for a checkup.

Here are some common symptoms to look for:

• Creamy white patches on the tongue. These could be a fungal infection known as thrush caused by an imbalance of bacteria in the mouth, according to WebMD. Most common in babies, oral thrush can occur after an illness, stress, or prolonged use of antibiotics. See your dentist for medication to help.
• A hairy tongue. If you tongue looks furry, it could be the result of excess protein buildup. According to WebMD, it should go away if you use a tongue scraper.
• Black tongue. While hairy tongues can also be black in color, taking an antacid with bismuth such as Pepto Bismol, may also darken the muscle. According to Healthline, when bismuth reacts with traces of sulfur in your mouth, it can stain your tongue black.
• Red tongue. A raspberry-colored tongue could be the result of something you ate, but it could be caused by an underlying condition, according to Medicinet. Have your doctor check for vitamin deficiencies, Kawasaki disease, or other infections. In rare cases, patches of red on your tongue may be premalignant.
• Burning sensation. If your tongue feels like it's on fire, it could be "burning mouth syndrome," a problem with the nerves in your tongue, says WebMD. If could be also caused by diabetes, dry mouth or infections.
• Smooth tongue. If there are no small bumps on the tongue and it looks glossy red, this could be a sign of vitamin B deficiency, Dr. Jacob Teitelbaum, author of "Real Cause, Real Cure," tells Newsmax.
• Macroglossia. When your tongue appears too big for the rest of your mouth, you may be suffering form macroglossia, which can be caused by hypothyroidism, and infection of allergies.
• Fissured tongue. We normally develop deep grooves in our tongues as we age, but fissures can also indicate psoriasis and Sjogren's syndrome. Experts say these are usually harmless and that bushing them helps clear away food particles and bacteria. If these become bothersome, your doctor may be able to help by identifying the underlying cause.