Tongue ulcers are most often canker sores, small round sores that form on the soft tissue inside your mouth. They’re rarely dangerous, but they can be surprisingly painful, especially when you eat, drink, or talk. The cause is usually something straightforward: a minor injury, stress, or a nutritional gap. Less commonly, tongue ulcers signal an underlying health condition that needs attention.
Canker Sores: The Most Likely Cause
If you’re looking at a single round or oval sore with a white or yellow center and a red border, you almost certainly have a canker sore (aphthous ulcer). These appear inside the mouth, on the tongue, inner cheeks, or lips. They don’t have a single known cause, but common triggers include stress, minor mouth injuries, smoking, and nutritional deficiencies in folic acid, iron, or vitamin B12.
Canker sores are not contagious and are not caused by a virus. This is what separates them from cold sores (fever blisters), which are caused by the herpes simplex virus and almost always appear on the outside of the mouth around the lips. Cold sores look like clusters of small fluid-filled blisters, while canker sores are flat, open ulcers. If your sore is inside your mouth on the tongue, it’s far more likely to be a canker sore.
Physical Injury and Irritation
One of the most common reasons for a tongue ulcer is simple mechanical damage. Biting your tongue while eating or talking can break the surface tissue and leave an ulcer that takes days to heal. Dental work like cavity fillings can nick or irritate the tongue. Braces, retainers, and ill-fitting dentures create ongoing friction that produces sores in the same spots repeatedly.
A sharp or chipped tooth edge is a particularly sneaky culprit. You may not even notice it with your finger, but your tongue rubs against it hundreds of times a day. If you keep getting ulcers in the same location on your tongue, check whether a rough tooth edge lines up with that spot. A dentist can smooth it down in minutes.
Nutritional Deficiencies
Your tongue is one of the first places to show signs of certain vitamin and mineral shortages. Low levels of vitamin B12, folate (vitamin B9), or iron can cause a sore, reddened tongue along with mouth ulcers. These deficiencies reduce your body’s ability to maintain healthy tissue in the mouth, making the tongue more vulnerable to breakdown.
If your tongue ulcers keep coming back and you can’t pin them on an obvious injury or trigger, it’s worth considering whether your diet is providing enough of these nutrients. B12 deficiency is especially common in vegetarians and vegans, older adults, and people with digestive conditions that reduce nutrient absorption. Other symptoms to watch for include fatigue, pale skin, and a tingling or numb feeling in your hands and feet. A simple blood test can confirm or rule out a deficiency.
Viral Infections
Certain viruses cause ulcers specifically on the tongue. The herpes simplex virus (usually type 1) can cause a condition called herpetic stomatitis, where blisters form on the tongue, cheeks, roof of the mouth, and gums, then pop and turn into open ulcers. This is different from the typical cold sore on the lip. It often comes with a high fever, sometimes reaching 104°F, which may appear a day or two before the blisters show up.
Herpetic stomatitis is most common in young children encountering the virus for the first time, but it can affect adults too, particularly those with weakened immune systems. Coxsackievirus, the cause of hand, foot, and mouth disease, also produces painful mouth and tongue ulcers alongside a rash on the palms and soles. Both infections are self-limiting, meaning they resolve on their own, typically within one to two weeks.
Underlying Health Conditions
Tongue ulcers sometimes point to a systemic condition happening elsewhere in the body. In some cases, mouth sores are actually the first visible sign of disease before other symptoms appear.
Crohn’s disease, an inflammatory bowel condition, can cause deep linear ulcers in the mouth. Pemphigus vulgaris, an autoimmune condition affecting the skin and mucous membranes, often starts with diffuse, painful oral ulcers before skin blisters develop. Lupus can produce irregularly shaped ulcers in the mouth. Celiac disease, which involves an immune reaction to gluten, is another condition linked to recurrent mouth sores.
Erosive lichen planus, a chronic inflammatory condition, causes redness and painful ulceration in the mouth with distinctive white lines radiating from the edges. These conditions are uncommon, but they’re worth being aware of if your tongue ulcers are severe, recurrent, or accompanied by other symptoms like digestive problems, joint pain, skin changes, or unexplained weight loss.
When Tongue Ulcers Need Attention
Most canker sores heal on their own within one to two weeks. The timeline matters here. An ulcer that hasn’t healed after two weeks deserves a closer look from a doctor or dentist, especially if it’s unusually large or painful, or if you’re experiencing other symptoms alongside it.
Tongue cancer, specifically squamous cell carcinoma, can look like an ulcer that simply won’t go away. Warning signs include a red or grayish ulcer on the tongue that persists beyond two weeks, a lump on the side of the tongue that bleeds easily, red or white patches, or thickening of the tissue. These features don’t guarantee cancer, but they do warrant evaluation. A biopsy may be recommended for oral ulcers lasting longer than three to four weeks to rule out malignancy.
Easing the Pain at Home
While you wait for a tongue ulcer to heal, a saltwater or alkaline rinse can reduce pain and help keep the area clean. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish gently and spit. You can repeat this several times a day.
Avoiding acidic foods like citrus, tomatoes, and vinegar-based dressings will make a noticeable difference in pain levels. Spicy foods and anything with rough or sharp edges (chips, crusty bread) can further irritate the sore. Soft, cool foods are the easiest to tolerate while your tongue heals.
For ulcers that are particularly painful or slow to resolve, prescription options exist. Steroid-based pastes or dissolving tablets applied directly to the ulcer reduce inflammation and speed healing. Your dentist or doctor may also prescribe a medicated mouth rinse that combines a numbing agent with an antacid coating to provide temporary pain relief. These treatments are typically used several times daily for a few days until the ulcer starts to close.
Recurrent Ulcers and What They Mean
Getting a canker sore once or twice a year is normal and usually nothing to worry about. Getting them every few weeks is a different story. Recurrent aphthous ulcers affect roughly 20% of the general population and can significantly impact quality of life when they’re frequent or severe.
If your tongue ulcers keep returning, start paying attention to patterns. Do they appear after stressful periods? After eating certain foods? Around your menstrual cycle? Keeping a simple log can help you identify triggers. The most productive next step is usually a blood test checking iron, B12, and folate levels, since correcting a deficiency often reduces or eliminates recurrent sores. If blood work comes back normal and ulcers persist, screening for autoimmune or inflammatory conditions may be appropriate.