Originally published October 18, 2016. Updated February 7, 2022.
One of the most important oral structures that is often overlooked and can be a manifestation of systemic disease is the tongue. The intent of this article is to provide the dental health professional and the patient with an aid to examining the tongue, recognizing the characteristics of a normal disease-free tongue, and identifying the top five pathologies most likely to affect the tongue that could represent larger systemic issues.
How to examine the tongue
- Touch the tip of the tongue to the roof of the mouth and inspect the ventral surface (the underneath portion of the tongue).
- Protrude the tongue straight out (stick tongue out) and inspect for deviation, color, texture, and masses.
- Hold the tongue with gauze in one hand while palpating the tongue between the thumb and index finger of the other, noting any masses and/or areas of tenderness.
Characteristics of a healthy tongue
- Color: The tongue should be a pinkish to reddish color on the dorsal (top) and ventral (underneath) surfaces. The ventral surface may be bluish in color and have some visible vasculature.
- Texture: The tongue should have a rough dorsal surface due to papillae (taste buds). There should be no hairs, furrows, or ulceration. The ventral side of the tongue should have a smooth surface.
- Size: The tongue should fit comfortably in the mouth with the tip against the lower incisors. The sublingual glands should not be displaced.
Related reading: COVID-19 tongue
Changes in the tongue that can represent disease
Change in surface texture—
Atrophic (smooth tongue):
- The most obvious cause of an atrophic tongue is the use of dentures and the mechanical exfoliation of the dorsal surface (rubbing of the surface of the tongue that makes it smooth).
- Nutritional deficiencies, especially vitamin B12deficiency (pernicious anemia), can also be a root cause (figure 1). Other deficiencies that can contribute include vitamin B3, B6, B9, and iron.
Changes in color—
- Oral candidiasis (thrush) is the result of an infection byCandida albicans (figures 2 and 3). This most typically occurs in patients with some form of immunosuppression (e.g., HIV), diabetes, chronic use of dentures without hygiene, and/or antibiotic use (usually over long-term periods). Painless white plaques on the tongue or oropharynx that can be removed and may result in bleeding are the hallmark of this fungal infection.
- Oral lichen planus (figure 4) is a chronic inflammatory condition caused by an autoimmune response. It is characterized by a white lacelike pattern called reticular lichen planus.
- Geographic tongue (figure 5) is a benign condition in which discolored, painless patches of the tongue appear and then reappear from atrophy, often in a different distribution. This is seen in 1%–3% of the population. Recent evidence, however, suggests that geographic tongue may be linked with a Vitamin B3 deficiency and inflammation of the intestine or “leaky gut/GALT/gut-triggered immune issues.”
- Vitamin deficiency in vitamin A, vitamin B2, B3, B6, B9, and B12
The most obvious cause of a red tongue is due to color in food or drink or acidic foods that can cause temporary redness and discomfort. However, a red tongue can be a sign of an underlying medical condition. Some red color changes on the tongue (“strawberry tongue”) could be related to a vitamin deficiency (B2, B6, B9, B12), iron deficiency, Kawasaki disease, or a strep infection (scarlet fever).
A black tongue is usually a harmless condition that can be caused by chlorhexidine rinses, medications, smoking, antibiotic use, poor oral hygiene, soft diet, or dry mouth (figure 6). Associated with elongated tongue papillae, the cause is thought to be a change in the normal bacteria in the mouth after antibiotic treatment or use of products that contain bismuth (sulfa), such as Pepto-Bismol.
Changes in size—
Macroglossia is swelling or enlargement of the tongue that can be caused by
- routine things such as allergies, insect bites, and trauma (from biting the tongue and/or burning the tongue).
- medications such as ACE inhibitors, NSAIDs (nonsteroidal anti-inflammatory drugs), and aspirin.
- amyloidosis, which is characterized by new-onset macroglossia in an adult.
Microglossia, or a small tongue, may result from damage to the upper motor neurons of the corticobulbar tracts that innervate the tongue. This condition presents with a small, stiff tongue. In newborns, there may be an apparent microglossia that results from a congenitally short lingual frenulum (ankyloglossia), commonly known as tongue-tie.
Changes in taste—
Complete loss of taste is called ageusia, partial loss of taste is called hypogeusia, and a distorted sense of taste is called dysgeusia.
Contributors to changes in taste:
- Medications usually cause a metallic taste, and these are associated with some forms of antibiotics; chlorhexidine rinses; antihistamines; antifungals; antipsychotics; blood pressure, diabetes, seizure, and Parkinson’s disease medications; among others.
- COVID-19 has been associated with alterations in smell and taste due to the effect of SARS CoV-2 virus on proteins associated with the ACE2 receptors in the tongue and nose.
- Xerostomia (dry mouth), colds or flu, smoking, and nutritional deficiencies (vitamin B12, vitamin C, and zinc).
When examining ulcers of the tongue, it is important to note their size, number, color, distribution, and whether they cause the patient any discomfort. Lesions that do not heal or regress in 10–14 days should be of concern and either biopsied or referred to a specialist.
An aphthous ulcer is a frequently encountered painful form of ulceration. The ulcer appears in one of several patterns: minor, major, or herpetiform.
- Minor aphthous ulcers (figure 7) are usually 2 mm to 8 mm in size and spontaneously heal within 14 days.
- Major aphthous ulcers are greater than 1 cm in size and may scar when they heal.
- Herpetiform ulcers are pinpoint in size, often occur in multiples, and may coalesce to form a larger ulcer.
Recurrent aphthous ulcers:
A recurrent aphthous ulceration occurs in some systemic illnesses, including Crohn’s disease, celiac disease, Behcet’s syndrome, pemphigus, herpes simplex, histoplasmosis, and reactive arthritis (Reiter’s syndrome).
Erythroplakia and leukoplakia:
- Erythroplakia (figure 8) is a red area or lesion on the tongue that cannot be rubbed off.
- Leukoplakia has the same definition, just white in color.
- Erythroleukoplakia is a lesion with a combined white and red appearance and is usually considered to have premalignant potential. Erythroplakia and erythroleukoplakia have an increased risk of premalignancy compared to leukoplakia. In addition to appearance, there is cause for concern if the lesion or sore does not go away or grows larger.