Why does a burning feeling in the tongue and mouth happen?

The burning you feel in your tongue or mouth does not have a single cause; several different reasons can produce the same symptom. In some patients, the cause is clear and treatment resolves it; in others, the examination and tests come back clear, and the burning carries on anyway. We deal with this second group separately below; the right approach is not to confuse the two.

When an underlying cause can be found, it is called secondary burning mouth syndrome; the most common ones are dry mouth, a vitamin or mineral deficiency, a fungal infection, uncontrolled blood sugar and hormonal changes. When the examination and tests show no cause at all, the condition is called primary burning mouth syndrome; this distinction matters because it changes the approach to treatment.

Dry mouth is the most common companion of burning. Saliva keeps the tissue moist and also acts as a buffer against acid and irritants; when the amount of saliva drops, the mucosa is irritated more easily and a burning feeling appears. Many medicines, particularly some blood pressure medicines, antihistamines and antidepressants, dry the mouth as a side effect; talk to your doctor about which medicine might be responsible, and do not stop it on your own decision. As you get older, the salivary glands can also slow down; this is why the same medicine may make no difference in a younger patient but cause noticeable dryness in an older one.

Iron, B12 and folic acid deficiency thin the surface of the tongue and the mouth's mucosa, setting the stage for burning. These deficiencies usually come with other signs too: tiredness, paleness, a smooth-looking tongue. In a patient who comes in with burning as the only complaint, your doctor may request these tests.

In patients who wear a denture, a common cause of burning is a fungal infection developing underneath it, a condition known in dentistry as denture stomatitis. If a denture is worn constantly without being taken out at night, the moist environment underneath becomes suitable for the fungus to multiply; the burning is usually felt in the area where the denture sits, together with redness. This condition improves with denture hygiene and, if needed, antifungal treatment.

Uncontrolled blood sugar can also affect the mouth's mucosa and contribute to burning; it both increases dry mouth and sets the stage for a fungal infection. If you have diabetes and you have developed burning, tell both your dentist and your doctor; once blood sugar is brought under control, burning linked to this cause is seen to ease, though this improvement can take weeks and happens only through treatment your doctor supervises.

Your dentist and your doctor look at different things. Your dentist assesses the inside of your mouth, your denture, the appearance of your tongue, and the toothpaste and mouthwash you use; your doctor reviews deficiencies, blood sugar, your thyroid and your medicines through blood tests. When neither side finds a cause, the honest truth is this: in some patients, the cause of the burning cannot be clearly identified, and in that case treatment targets the burning itself.

The points on the left show that a cause can probably be found and can improve with treatment; those on the right call for wider investigation.

For a complaint of burning, you need to see your dentist first, and your doctor when needed; this page does not replace that visit.

1. 1

   The history

   You are asked when the burning started, how it changes through the day, which food or product makes it worse, the medicines you take and whether you wear a denture.

2. 2

   An examination of the inside of your mouth

   Your dentist assesses the appearance of your tongue and mucosa, underneath your denture, any signs of a possible fungal infection, and the contents of the toothpaste and mouthwash you use.

3. 3

   A review of your list of medicines

   Whether the medicines you take dry your mouth is checked. Even if a medicine is thought to be having an effect, any change is made only on your doctor's decision.

4. 4

   A referral for blood tests

   If there is no clear finding inside the mouth, you are referred to your doctor for iron, B12, folic acid, blood sugar and, if needed, thyroid levels.

5. 5

   Treatment if a fungal infection is found

   If a fungal infection is seen under a denture or on the tongue, antifungal treatment and denture hygiene are recommended.

6. 6

   The outcome: was a cause found, or not

   If a cause is found, treatment for it is planned. If the examination and tests come back clear, the condition is treated as primary burning mouth syndrome, and the burning itself becomes the target of treatment.

There is no single treatment for burning; the steps below vary depending on the cause that is found.

The points below show what you lose by ignoring the burning or trying to get past it the wrong way.

How long it takes depends on the cause that is found.

1. With dry mouth

   With measures to increase moisture and, if needed, a change in medicine, the burning can noticeably ease within days.

2. With a fungal infection

   With antifungal treatment and denture hygiene, the burning usually eases within a few weeks.

3. With treatment for a deficiency

   Once treatment for iron, B12 or folic acid begins, the burning can take weeks to ease; this is a process your doctor monitors.

4. When no cause is found

   The course of primary burning mouth syndrome varies from person to person; it eases over time in some patients, while in others it follows an up-and-down course.

Because treatment for burning depends entirely on the cause that is found, giving a single figure here would not be right: for some patients, changing a product is enough, while others need blood tests and assessment by more than one specialist. These are the items that determine the scope:

Whether blood tests are needed

Iron, B12, folic acid and blood sugar tests fall under your doctor's remit, not your dentist's.

Whether treatment for a fungal infection is needed

Antifungal treatment and adjusting a denture are a separate procedure and cost item.

How many specialists need to be involved

For some patients, a dentist alone is enough; for others, a doctor, and sometimes another relevant specialist too, becomes part of the process.

Whether a cause is found

When no clear cause is found, the process becomes not a one-off but ongoing follow-up that needs periodic reassessment.