Tongue sores most often come from minor physical injury, like accidentally biting your tongue or irritating it with rough food. They can also result from stress, nutritional deficiencies, infections, or immune system responses. Most tongue sores are canker sores, which are harmless and heal on their own within one to two weeks.
Canker Sores: The Most Common Cause
Canker sores (aphthous ulcers) are small, shallow ulcers that appear on the tongue, inner cheeks, or gums. They’re typically round with a white or yellowish center and a red border. They hurt, sometimes enough to make eating uncomfortable, but they’re not contagious and they’re not dangerous.
The exact cause isn’t fully understood, but the immune system plays a central role. Something triggers an abnormal inflammatory response in the soft tissue of your mouth, and the result is a painful open sore. Genetics matter too. If your parents got frequent canker sores, you’re more likely to as well.
Common triggers include:
- Physical injury: biting your tongue, scraping it on braces or retainers, or irritation from dental work
- Stress and poor sleep: college students famously get canker sores during finals week
- Certain foods: acidic fruits like oranges and pineapples, plus chocolate, peanuts, and eggs can worsen flare-ups
- Toothpaste ingredients: sodium lauryl sulfate and other harsh detergents in toothpaste are linked to outbreaks
- Hormonal shifts: some women notice sores around their menstrual period
If you get canker sores frequently, switching to a gentler toothpaste is one of the simplest things to try first.
Nutritional Deficiencies
Low levels of iron, vitamin B12, or folate can cause recurring tongue sores or a condition called glossitis, where the tongue becomes swollen, red, and painful. The NHS lists “a sore or red tongue, sometimes with mouth ulcers” as a direct symptom of B12 or folate deficiency anemia. If your sores keep coming back and you can’t pin down an obvious trigger like stress or injury, a simple blood test can check these levels. Correcting the deficiency usually stops the sores.
Infections That Affect the Tongue
Oral thrush is a fungal overgrowth that produces creamy white, slightly raised patches on the tongue or inner cheeks. The patches look a bit like cottage cheese and can bleed slightly if you scrape them. Thrush often causes a burning sensation, loss of taste, and a cottony feeling in the mouth. It’s more common in people who wear dentures, use inhaled corticosteroids for asthma, have weakened immune systems, or have recently taken antibiotics.
Herpes simplex virus can also cause sores on the tongue, though it more commonly affects the lips and gums. Herpes sores tend to appear as clusters of small, fluid-filled blisters that burst and leave shallow ulcers. Unlike canker sores, herpes is contagious and often comes with tingling before the sores appear.
Bacterial infections are less common but can develop if an existing sore gets infected, especially with poor oral hygiene.
Underlying Health Conditions
Persistent or severe tongue sores sometimes point to a broader health issue. Conditions linked to recurring mouth ulcers include celiac disease, Crohn’s disease, lupus, Behçet’s disease, and reactive arthritis. In these cases, mouth sores are one piece of a larger pattern of symptoms. If you’re dealing with frequent ulcers alongside digestive problems, joint pain, or fatigue, it’s worth mentioning the sores to your doctor since they may help with diagnosis.
How to Relieve the Pain
Most tongue sores don’t need treatment and will clear up within a week or two. But while they’re active, over-the-counter numbing gels containing benzocaine can take the edge off. Products with hydrogen peroxide work as antiseptic rinses that keep the area clean and may speed healing slightly. For more severe or frequent sores, prescription options include steroid-containing mouth rinses that reduce inflammation and topical pastes applied directly to individual sores.
In the meantime, avoiding spicy, salty, and acidic foods helps. So does rinsing with warm salt water a few times a day. Applying the gel or paste as soon as a sore appears, rather than waiting until it’s fully developed, tends to work better.
When a Sore Could Be Something Serious
The key number to remember is three weeks. A normal canker sore heals within one to two weeks. If a sore on your tongue lasts longer than three weeks, it needs professional evaluation.
Oral cancer can look like a persistent sore or lump that simply doesn’t heal. One important difference: while canker sores are reliably painful, oral cancer lesions are often painless, at least early on. Other warning signs include thickening of tissue in the mouth or throat, difficulty swallowing or chewing, voice changes, and unexplained weight loss. A sore that’s unusually large, accompanied by fever, or paired with swollen lymph nodes also warrants a closer look, even before the three-week mark.
Oral cancer sores can appear as red or white patches anywhere in the mouth, including the tongue, gums, cheeks, and throat. They don’t have the neat round shape and red border of a typical canker sore. The distinction isn’t always obvious to the untrained eye, which is why persistence is the most reliable signal that something needs attention.