A sore on the tongue: a bite, a mouth ulcer, and when is an examination needed?

The tongue is the most mobile organ in the mouth. It touches the teeth constantly while you speak, swallow and chew; that is why it is one of the places where mouth sores are common. Among the causes of a single mouth sore, the NHS lists biting the cheek, a badly fitting denture, a rough filling and sharp teeth, a sore made by hard food or a hot drink, allergy, stress, hormonal changes, vitamin deficiencies, some medicines and stopping smoking. MSD Manuals, too, writes of a habit of biting the lip or cheek, a poorly fitting denture and broken or sharp teeth as mechanical causes that start a sore.

The cause of a bite or burn sore is clear: you remember when it happened. A bite is generally on the side edge of the tongue, at the level where the teeth close; a burn is mostly on the tip and upper surface of the tongue, where the hot mouthful first touched. Both shrink within days if the cause is not repeated. If you keep biting the same place again and again at meals, the sore starts from the beginning each time; this is the most common and most innocent explanation for a sore dragging on.

A mouth ulcer appears under the tongue and on its side edges, that is, on the soft, moving parts of the mucosa. It is round or oval, with a yellowish-grey centre and a red border, and markedly painful to the touch. There is no bite or tooth edge behind it, it appears by itself and most often heals in a week or two. Recurring from time to time in different places in the same person is the typical feature of a mouth ulcer. We have explained the general course of mouth ulcers in detail on our page on mouth sores and ulcers; here we focus on the points specific to the tongue.

The cause most often overlooked on the tongue is a sharp edge on the tooth opposite the tongue. A broken filling, a crumbled corner of a tooth, a tilted molar or a pointed edge of a denture touches the same spot on the tongue hundreds of times a day. This sore does not come and go like a mouth ulcer; it always stays in the same place, does not heal unless its cause is dealt with, and its edge can thicken over time. Once the edge is smoothed, however, it generally starts to shrink within a few days.

A review examining recurrent mouth sores groups the causes under seven headings: trauma, chemical irritation, mouth ulcers, medicine-related sores, infections, diseases that affect the skin and mucosa together, and autoimmune or systemic diseases. The NHS, too, asks you to see a doctor if there are also sores elsewhere on the body or painful, swollen joints alongside. This picture suggests that the sore on the tongue may not be a problem confined to the mouth; the assessment is made by a GP or by internal medicine.

The possibility that really needs attention is mouth cancer. Among the symptoms of mouth cancer, the NHS lists a mouth sore that lasts longer than 3 weeks, a red or white patch inside the mouth, a lump in the mouth or on the lip, difficulty swallowing and speaking, a lump in the neck and unintended weight loss. In a small study from Iran that examined tongue cancers from one centre's archive, the most common site was the side edge of the tongue (36.8 per cent). This does not mean that every sore on the side edge of the tongue is suspicious; bite sores and tooth-edge sores appear in exactly that place too. But if a sore on the side edge has lasted beyond 3 weeks, there is no longer any sense in taking it for a bite and waiting.

There is one more misleading picture. An eosinophilic ulcer, seen on the mucosa of the mouth, produces a sore with a hardened surround that looks as if it had been punched out, and its appearance raises a suspicion of cancer. The review on this subject states that the sore is benign and most often heals by itself, but recommends that the trigger be removed and the sore monitored and, if necessary, a biopsy taken. In other words, not every hard-edged sore is cancer; but which is which has to be distinguished not by looking at the appearance but with a tissue sample.

If you wake from sleep with the side edge of your tongue bitten, pay attention to this too. In a small study in an epilepsy monitoring unit, all eight patients with a bite on the side edge of the tongue had a documented epileptic seizure; of 45 people who had fainted, the tongue had been bitten in only one, and that was at the tip of the tongue. This study is small and from a single centre, and it does not establish a diagnosis of seizures. But if tongue bites whose cause you do not know come together with a morning headache, muscle pain, grogginess or bed-wetting, tell your GP about it.

The pictures in the first list suggest ordinary causes, those in the second list situations in which you should stop waiting and be examined. This is not a diagnosis; it is an ordering to help you decide which route to take.

The order deliberately starts from the emergency, then moves on to the checks you can do at home and to what the doctor or dentist does. This page is not a substitute for an examination.

1. 1

   First rule out the emergency signs

   The NHS asks for emergency help to be called immediately when the tongue, lip, mouth or throat swells suddenly, when you are struggling to breathe, when your throat feels tight or when you cannot swallow; in Turkey, call 112. If bleeding from a bite or a cut does not stop with pressure, if blood is spurting or if the wound is very deep or large, also call 112 or go to the nearest A&E department. Do not drive yourself.

2. 2

   Stop the bleeding by pressing

   After a bite, press steadily on the wound for a while with clean gauze or a clean cloth. Because the tongue has a rich blood supply, even a small bite can bleed alarmingly; it is expected to stop with pressure. If it does not stop, go back to the previous step.

3. 3

   Check the tooth opposite it

   With a clean finger or with your tongue, feel the edge of the tooth directly opposite the sore; in the mirror, close your teeth and look at where that spot on the tongue touches. If you feel a broken filling, a crumbled corner or a pointed denture edge, you may have found the cause. Do not try to smooth this edge yourself with a file or a nail file; your dentist does it in a few minutes.

4. 4

   Photograph the sore and note the date

   In good light, put your tongue out, take a photograph of the sore and write down the date. Repeat this every few days. This is the most reliable way of seeing whether the sore is shrinking; it also makes it easier to count towards the 3-week threshold.

5. 5

   Start self-care

   The NHS recommends using a soft-bristled brush, drinking cold drinks through a straw and choosing soft foods; and avoiding very spicy, salty and acidic foods, hard and crunchy foods such as toast, very hot drinks and toothpastes containing sodium lauryl sulphate. You can dissolve half a teaspoon of salt in a glass of warm water and rinse; do not swallow it.

6. 6

   An examination and dealing with the cause

   The dentist or GP looks at the position of the sore, its edge, any hardness beneath it and the tooth opposite it; they also check the rest of the mouth and feel the lymph glands in the neck. If there is a sharp edge, that is smoothed first and the sore is monitored for a while. If the sore does not heal within about two weeks after the edge has been smoothed, be seen again without waiting for the 3 weeks to be up. With recurrent sores, a blood test or referral to other departments may come into it.

7. 7

   A tissue sample for a sore that does not heal

   For a sore that does not heal even though its cause has been dealt with, that is hardening or that has lasted beyond 3 weeks, the doctor may recommend taking a small tissue sample (a biopsy). It is done under local anaesthetic and this is the method that makes the diagnosis; it is also the way to distinguish benign sores whose appearance resembles cancer.

There is no single treatment for a sore on the tongue; what caused it determines the route.

The following are mistakes that are common with this complaint and that come at a price.

The times below are thresholds based on the sources. If the course of your sore does not fit them, stop monitoring.

1. The first days

   With a bite, a burn and a mouth ulcer, pain is generally at its most intense in the first days. Bleeding should have stopped with pressure.

2. After the edge has been smoothed

   A rubbing sore should start to shrink visibly once the cause has been removed. If it does not heal within about two weeks, be seen again without waiting for 3 weeks.

3. 1–2 weeks

   The NHS writes that most mouth sores clear by themselves in this time. At this point the sore should either have healed or have shrunk markedly.

4. 3 weeks

   The NHS threshold for seeing a doctor. A tongue sore that lasts beyond this time should be examined, whatever its cause is thought to be. MSD Manuals gives a shorter time: it writes that every mouth sore lasting 10 days or longer should be seen by a dentist or doctor to make sure it is not cancer or a precancer.

Because most sores on the tongue heal without requiring any procedure, the cost is mostly to do with dealing with the cause and, if necessary, clarifying the diagnosis. The items that determine the scope:

The cause

A bite or mouth ulcer that heals by itself, a tooth edge that needs the filling renewed and a denture that has to be remade are very different items.

Whether a blood test is needed

The tests requested for recurrent sores are carried out within the scope of a GP or internal medicine.

Biopsy and pathology

Taking a tissue sample from a sore that does not heal and having it examined in pathology are separate items.

Treatment according to the diagnosis

Monitoring may be enough, or a picture that requires surgery or long-term follow-up may emerge.