Pain under the tongue usually comes from something minor and treatable, like a canker sore, an irritated frenulum, or a blocked salivary gland. The area beneath your tongue (called the floor of the mouth) is packed with sensitive structures: salivary glands, ducts, a thin band of tissue connecting your tongue to the floor of your mouth, and delicate mucous membranes. Any of these can become inflamed, injured, or infected, and because the tissue is so thin and nerve-rich, even small problems tend to hurt more than you’d expect.
Canker Sores
Canker sores are one of the most common reasons for pain under the tongue. These small, round or oval ulcers have a white or yellow center with a red border, and they form on the soft tissues inside your mouth, including on or under the tongue. Minor canker sores are usually small and heal on their own within one to two weeks without scarring. Major canker sores are deeper, larger, and can take up to six weeks to heal, sometimes leaving scars behind.
Triggers vary from person to person. Biting or burning the underside of your tongue, acidic foods, stress, and hormonal shifts can all set one off. If you get them frequently, it may be worth looking into nutritional gaps (more on that below). In the meantime, rinsing with a saltwater solution, half a teaspoon of salt dissolved in a cup of warm water, can reduce irritation and help the area heal faster.
Salivary Gland Blockages
Your sublingual glands sit directly under your tongue, and each one has tiny ducts that release saliva into your mouth. Sometimes small calcium-based stones form inside these ducts and block the flow of saliva. When that happens, the gland swells up, often creating a painful lump you can feel with your tongue or finger. The telltale sign of a salivary stone is that the pain and swelling get noticeably worse when you eat or even think about eating, because your gland is trying to push saliva past the blockage.
If saliva pools behind the stone for too long, the gland can become infected, adding fever and redness to the mix. A doctor can often feel the stone during an exam or spot it on an ultrasound or CT scan. Small stones sometimes pass on their own with gentle massage and hydration. Larger ones may need to be removed in a quick outpatient procedure.
Ranulas and Mucous Cysts
A ranula is a type of fluid-filled cyst that forms on the floor of the mouth, almost always originating from the sublingual gland or its ducts. It looks like a soft, bluish, dome-shaped swelling under the tongue. Ranulas develop when mucus leaks out of a damaged duct and pools in the surrounding tissue rather than draining into the mouth normally.
Most ranulas stay confined to the floor of the mouth, but in rare cases the fluid tracks downward through the muscles of the jaw and causes visible swelling in the neck (called a “plunging” ranula). Small ranulas may not hurt much, but larger ones can make it uncomfortable to eat or talk. Treatment typically involves draining the cyst or removing the affected gland to prevent recurrence.
Frenulum Irritation or Injury
The lingual frenulum is the small band of tissue that connects the underside of your tongue to the floor of your mouth. You can see it if you lift your tongue and look in a mirror. This tissue can become sore or swollen from surprisingly minor events: eating something with a sharp edge, kissing, a sports impact, or even friction from braces or a dental appliance. A torn frenulum bleeds and stings but usually heals quickly on its own.
Some people are born with a frenulum that’s unusually short or thick, a condition called tongue-tie. While tongue-tie is most often discussed in infants, adults with the condition can experience restricted tongue movement, difficulty swallowing, and chronic soreness under the tongue, especially after extended talking or eating.
Vitamin Deficiencies
Persistent burning, soreness, or inflammation under and around the tongue can sometimes trace back to nutritional gaps rather than a visible sore or lump. Deficiencies in B vitamins, particularly B12, B1, B2, and B6, along with folic acid, zinc, and iron, have all been linked to burning mouth symptoms and chronic tongue inflammation.
A B12 deficiency is especially relevant. It can cause glossitis (a swollen, painful tongue), recurring ulcers, burning sensations, and numbness. Iron deficiency produces a similar picture: burning mouth, chronic tongue inflammation, and pale mucous membranes. In many cases, these symptoms resolve after the deficiency is corrected with supplementation. If your pain is more of a diffuse burning than a localized sore, and you’ve noticed other signs like fatigue or tingling in your hands and feet, a simple blood test can check your levels.
Infections
Bacterial and viral infections can target the floor of the mouth. An infected salivary gland, as mentioned above, causes localized swelling and pain. But infections can also develop around the roots of lower teeth, in the gums, or in the soft tissue itself, and the pain often radiates to the area under the tongue.
One rare but serious infection to know about is Ludwig’s angina, a fast-spreading bacterial infection of the tissue beneath the tongue and along the jaw. Symptoms come on suddenly and can include jaw or neck swelling, fever, drooling, tongue tenderness, difficulty swallowing, and trouble breathing. This is a medical emergency. If you have rapidly worsening pain under your tongue combined with neck swelling and difficulty breathing or swallowing, you need emergency care immediately.
When the Pain Doesn’t Go Away
Most causes of pain under the tongue resolve within a week or two. A sore that does not heal is the one pattern worth paying close attention to. Floor-of-the-mouth cancer can start as a painless or mildly painful lesion, a persistent sore, a lump, or a patch of white or red tissue. Red patches in particular carry a higher chance of being cancerous or precancerous. People often mistake an early cancerous lesion for an abscess or infection, but infections heal while cancerous lesions do not.
Other signs include loose teeth without obvious dental cause, pain with swallowing, and difficulty moving the tongue. These lesions can also change over time. A biopsy that comes back benign can become cancerous months later, which is why monitoring matters. If you have a sore or lump under your tongue that hasn’t improved in two to three weeks, getting it examined is the right move. Early-stage floor-of-the-mouth cancers have far better outcomes when caught before they spread.
Simple Relief at Home
For mild pain from canker sores, minor frenulum irritation, or general soreness, a few simple steps can speed healing and reduce discomfort. Rinse your mouth with warm saltwater (half a teaspoon of salt per cup of warm water) two to three times a day. Avoid spicy, acidic, or very hot foods that can aggravate the area. Over-the-counter topical gels designed for mouth sores can numb the pain temporarily. Staying hydrated helps keep your salivary glands functioning smoothly and reduces the risk of duct blockages.
If the pain is severe, getting worse, accompanied by swelling in your neck or jaw, or lasting beyond two weeks without improvement, those are all signals that something beyond a minor irritation is going on and worth having examined.