The sensation of pain under the tongue can be confusing because this soft tissue space houses several important structures. This area contains the sublingual glands and the opening of the larger submandibular gland ducts. The lingual frenulum, the small band of tissue connecting the tongue to the floor of the mouth, also runs through this space. Pain in this highly sensitive region usually points to irritation of the surface lining or an issue with the underlying salivary gland system.
Problems with Salivary Glands and Ducts
Discomfort under the tongue often involves the submandibular salivary ducts (Wharton’s ducts), which release saliva near the frenulum. These ducts can be blocked by calcified deposits called salivary stones (sialolithiasis). The stones are most commonly found in the submandibular gland system.
This blockage causes pain and swelling, particularly during meals when saliva production increases. Since saliva cannot pass the stone, it backs up into the gland. This leads to painful, cyclical swelling that often subsides hours after eating. Small stones may pass naturally, but larger stones often require medical intervention.
If a blockage persists, it can lead to sialadenitis, an inflammation or bacterial infection of the salivary gland. Symptoms are generally more severe, including rapid swelling, tenderness, fever, or chills. The infection often arises when bacteria, such as Staphylococcus aureus, ascend the duct, a process made easier by reduced saliva flow.
Common Causes of Injury and Inflammation
Superficial pain under the tongue often results from direct physical injury or localized irritation. Accidental trauma is frequent, such as biting the tissue while chewing or sustaining small cuts from sharp foods. Burns from consuming hot liquids or foods can also injure the sublingual mucosa.
Aphthous ulcers, commonly known as canker sores, are a frequent cause of localized pain in the soft tissues. These sores present as small, round, white or yellowish lesions surrounded by a red border and are not contagious. While their exact cause remains unclear, factors like emotional stress, minor trauma, and nutritional deficiencies may trigger their formation.
Irritation can also stem from chemical exposure or dental appliances. Harsh ingredients in some mouthwashes, such as sodium lauryl sulfate, may irritate the tissue. Sharp or broken edges on a tooth, retainer, or partial denture can rub against the soft tissue, creating a chronic sore.
Less Frequent Structural and Chronic Issues
Some structural issues, while less common than sores or stones, can cause noticeable swelling and discomfort. A ranula is a specific type of mucous cyst that forms when a salivary gland duct, usually from the sublingual gland, is damaged or blocked. This causes saliva to leak into the surrounding tissues, resulting in a soft, fluid-filled swelling that is typically clear or bluish.
While often painless initially, a ranula can grow large enough to interfere with speaking, swallowing, or chewing. In rare cases, the cyst can rupture through a muscle, causing a complex “plunging ranula” that presents as a swelling in the neck. Trauma or previous surgery to the mouth is a common precursor to its development.
Nutritional deficits can also manifest as chronic oral pain and inflammation. Deficiencies in specific B vitamins (B12 and folate) and low iron levels are linked to inflammation of the mouth lining and the tongue (glossitis). A lack of these nutrients can cause the oral mucosa to become thinned and more susceptible to painful ulceration.
Certain medications, especially those with anticholinergic properties, can reduce salivary flow, leading to dry mouth (xerostomia). This decreased saliva creates an environment where the sublingual tissue is more vulnerable to injury and infection.
When to Seek Professional Medical Care
While many causes of sublingual pain resolve on their own, certain symptoms indicate the need for prompt professional evaluation. Pain accompanied by a fever, chills, or a foul-tasting discharge suggests a possible infection requiring antibiotics. Rapid or significant swelling that makes it difficult to swallow, speak, or breathe should be treated as a medical emergency.
A persistent ulcer or lump that does not begin to heal within 7 to 10 days, or a firm, immovable mass, requires examination to rule out serious underlying conditions. Recurrent episodes of swelling and pain, especially those correlated with eating, should also be investigated to manage underlying salivary gland issues.