A burning tongue sometimes has a visible cause and sometimes presents with an entirely normal examination. How the two are distinguished and why the approach differs.
A burning tongue is easy for a patient to describe and slow for a clinician to resolve. In some patients the examination shows a clear finding and treatment is direct. In others the mouth looks entirely normal; that second group needs a different approach.
How the complaint is described
Patients usually describe a feeling like a scald from a hot drink. The burning most often concentrates at the tip and borders of the tongue and may spread to the palate and inner lips. Dry mouth and a change in taste often accompany it.
It typically starts mildly in the morning, builds through the day and peaks towards evening. Easing while eating is characteristic, and that detail distinguishes it from other oral pain.
Visible causes
In a substantial share of patients presenting with burning, the examination reveals an explanation. In this group the symptom resolves once the cause is addressed.
- Oral candidiasis — a white coating that wipes off
- Dry mouth from medicines or Sjögren's syndrome
- Structural variants such as geographic and fissured tongue
- A poorly fitting denture or acrylic allergy
- Acid contact from reflux
- Deficiency of iron, B12, folate and zinc
When the examination is normal: burning mouth syndrome
Where burning continues but there is no finding in the mouth and blood tests are normal, the condition is called burning mouth syndrome. It is a diagnosis of exclusion, reached after all other causes have been ruled out.
The mechanism is thought to involve a change in how the sensory nerves of the mouth function. The tissue is intact but the nerve is generating an incorrect signal. It is seen more often in women from middle age onwards.
Which tests are done
Assessment begins with blood tests: full blood count, iron, ferritin, B12, folate, zinc and fasting glucose. Thyroid function is also checked. A swab for candida is taken where needed.
Salivary flow can be measured; it is common for flow to be normal although the patient describes dryness, and this contributes to the diagnosis. The medication list is reviewed, as drugs that dry the mouth often play a part.
What makes the burning worse
Certain habits clearly aggravate the picture and most patients do not notice them. Mint and cinnamon flavoured products, alcohol-based mouthwashes and toothpastes containing sodium lauryl sulphate are the commonest culprits.
Acidic drinks, heavily spiced food, smoking and a habit of rubbing the tongue against the teeth also increase the burning. Removing these for a period can bring clear relief on its own.
How treatment is planned
Where there is a visible cause, treatment addresses it: antifungals for candida, replacement for deficiencies, adjustment for a denture problem. Results in this group are usually quick and satisfying.
In burning mouth syndrome the aim is to manage the symptom. Topical preparations, low doses of certain neuropathic pain medicines and behavioural approaches are used. The process needs patience and improvement is gradual.
Anxiety and the symptom
Anxiety is common here and works in both directions: it increases the symptom and is increased by it. A patient's fear that something serious is present in the mouth makes the burning more prominent.
Explaining clearly and convincingly that the examination is normal is therefore part of the treatment. Knowing there is no serious disease genuinely reduces the intensity of the symptom in most patients.
What helps at home
- Holding an ice chip or cold water in the mouth — the fastest relief
- Chewing sugar-free gum; it increases saliva and distracts
- Stopping mint and cinnamon products entirely for a while
- Switching to a toothpaste without sodium lauryl sulphate
- Using an alcohol-free, neutral-flavoured rinse
None of these is a treatment on its own, but together they clearly reduce how much the symptom affects daily life. Keeping a note for a week or two of which ones help is very useful at the review appointment.
When to seek help
An examination is needed where burning lasts more than two weeks, is worsening or affecting eating. Where there is a visible change in colour, a sore or thickening on the tongue, do not wait.
A one-sided symptom, one accompanied by numbness, or a palpable lump in the neck also requires prompt assessment. These findings usually point to a different condition.
