Doctors say the tongue is a great place to look for signs of trouble — even before other symptoms occur
While it’s not true that your tongue is the strongest muscle in your body (scientists argue it’s either the main jaw muscle or the gluteus maximus, the butt muscle), it’s definitely one of the most unique: The tongue can be a harbinger for the health of your entire body.
According to Dr. Matt Messina, assistant professor of dentistry at The Ohio State University, tongue and mouth tissues are more transparent than skin — so medical providers can more easily see signs of a medical condition beneath the surface.
“The tongue and mouth are a great place to look for signs of disease before a patient develops symptoms,” says Messina. “It may point us in a direction, suggesting we ask more questions.”
People tend to pick up on issues with their own tongues too. Dr. Edward Damrose, professor of otolaryngology at Stanford, says the tongue is loaded with sensory nerves, making it more sensitive than other parts of the body. The tongue is also used for everyday functions like speech, eating, and drinking. “If there’s something wrong, people will generally notice it pretty early,” he says.
Here are some of the most common tongue conditions doctors look for that can signal a larger health issue.
In a regular dental exam, Messina says one of the first things he checks for is a dry tongue. Most commonly, a dry tongue and mouth stem from basic dehydration that people can easily remedy with fluid intake. But it can also indicate a condition called xerostomia, in which the mouth’s salivary glands don’t produce enough saliva.
Messina says while xerostomia can be a congenital condition, it’s often a medication side effect — there are more than 600 over-the-counter and prescription medications that list dry mouth as a side effect, including antidepressants and antihistamines. If that’s the case, the dentist might recommend talking to a doctor about trying a medication with fewer side effects.
Some people experience a burning sensation on the surface of their tongues which is often accompanied by a metallic, bitter taste (or a loss of taste) as well as red patches on the tongue’s surface.
Messina says these uncomfortable symptoms sometimes trace back to a condition called geographic tongue, an inflammatory disorder of the mouth that’s generally more common in people with psoriasis. Doctor’s aren’t totally sure what causes geographic tongue, but it’s been linked with emotional stress, hormonal imbalances, and vitamin deficiencies.
A burning tongue can also be a sign of burning mouth syndrome, where people experience a chronic scalding sensation on their tongue, sometimes accompanied by loss of taste and dryness or numbness in the mouth. Burning mouth syndrome is considered its own condition, but it can also be a sign of separate conditions like GERD, food allergies, thyroid disorders, or anxiety and depression.
A fungal infection called candida albicans, often called thrush, could be to blame. Often, Messina says, that will make the doctor curious about deeper, systemic issues that led to the fungal growth.
“Generally, the body does a really good job keeping us from getting fungal infections, so a fungal infection of the mouth can indicate someone is immunocompromised in some way,” he says. “Otherwise healthy people often don’t develop fungal infections in their mouths, so we need to look at why that might be.”
Steroid medications for a respiratory condition or autoimmune diseases like lupus can impact immunity, potentially causing thrush. But if someone isn’t taking steroids, Messina says he’d refer a person to their primary care provider for a full exam.
“Sometimes, you can open up the mouth and tell right away someone has a serious problem.”
A wound or an ulcer that won’t heal on the tongue could be a sign of oral cancer, which both dentists and doctors regularly screen for if a person has risk factors like smoking or drinking.
Damrose says in cases of cancer, a patient will notice their symptoms persisting and getting worse. “A good rule of thumb is if a sore hasn’t healed in two or three weeks, go see an ear, nose, and throat specialist,” he says.
Dentists commonly screen patients for oral cancer at routine appointments, which Damrose says is an important way to catch it early. “Both the dental and medical system have a decent way of screening people,” he says. “But most people are more likely to be seeing their dentist regularly than an ENT.”
In addition to examining the tongue’s appearance, dentists and doctors also consider the tongue’s range of motion. “We want to make sure the tongue is protruding evenly and in a straight line, and that the patient can smoothly control it,” says Messina.
Messina says if a person has trouble swallowing or moving their tongue, they could have an infected salivary gland or a blocked salivary duct.
Difficulty moving the tongue could also be a sign of a stroke around the hypoglossal nerve, a cranial nerve involved in tongue movement, eating, chewing, and speaking. Dr. Daniel Allan, a family medicine doctor at the Cleveland Clinic, says he will often check out someone’s tongue motion if he’s concerned about a potential transient ischemic attack, commonly called a “mini-stroke.”
“A tongue exam can help a doctor determine the location of where a stroke could have happened, where the blood flow was disrupted,” he says. “I’d have the patient move the tongue side to side and make sure they can apply pressure on either cheek.”
In some people, an enlarged tongue can be a result of obesity. Studies show that an increase in body mass index is associated with a greater proportion of fat on the tongue.
A large tongue size can be linked to sleep apnea, a condition where people have lapses in breathing while sleeping, according to Dr. Kelly Glazer Baron, director of the Sleep-Wake Center at the University of Utah.
“We know that fat deposits and obesity are some of the biggest contributors to sleep apnea and that the size of the tongue can be a factor of why the airway is occluded,” she says.
If a person’s speech changes or they have a difficult time swallowing, a doctor might be concerned about a neurological condition. Damrose says in a tongue exam, he might notice one side of the tongue is paralyzed, that the tongue is shrinking, or that the patient is experiencing tongue tremors.
If all these symptoms are present, he says it’s almost certain the patient has Lou Gehrig’s disease, or ALS, a condition causing the death of neurons that control a person’s voluntary muscles. “Sometimes, you can open up the mouth and tell right away someone has a serious problem,” Damrose says.
White or gray patches on the sides of the tongue, called leukoplakia, can occur in smokers. In many cases, these patches can be resolved with lifestyle changes like quitting smoking.
A specific kind of leukoplakia, called hairy leukoplakia, has a more corrugated appearance. Damrose says it’s often seen in people with weakened immune systems caused by HIV or the Epstein-Barr virus. As with thrush, if a doctor finds hairy leukoplakia, they will likely do some digging to figure out why the patient’s immune system is compromised.
The tongue’s papillae, the small nipple-like structures that give the tongue its rough surface, grow in different cycles and eventually shed. If someone lacks good dental hygiene or isn’t regularly brushing, the shedding process will drag out, and the tongue will harbor bacteria. “The overgrown papillae and the bacterial debris can give the tongue a darker or black appearance,” says Allan.
Typically, better oral hygiene can restore papillae health, but Allan says overgrown, black papillae can be a sign of a suppressed immune system, such as uncontrolled diabetes.
Basic nutritional deficiencies — most commonly, folic acid and vitamin B-12 — can also distort the tongue’s color. “If those are deficient, the papillae might not mature properly, so they become red and glossy instead of the standard pale appearance,” Allan says.
Most people can improve their nutritional intake with diet and supplements, but Allan says some medical conditions can cause these deficiencies. For example, anemia or celiac disease can lead to low B12 levels, and alcoholism can cause a lack of folic acid in the body.
While Allan says he does a standard tongue exam on everyone who has a physical, he spends more time in an oral health exam with someone who drinks or smokes or people who have a head and neck complaint. “A tongue exam is part of a routine physical, but there are times we would want to pay extra attention,” he says.