Causes

The cause of burning mouth syndrome can be classified as either primary or secondary.

Primary burning mouth syndrome

When no clinical or lab abnormalities can be identified, the condition is called primary or idiopathic burning mouth syndrome. Some research suggests that primary burning mouth syndrome is related to problems with taste and sensory nerves of the peripheral or central nervous system.

Secondary burning mouth syndrome

Sometimes burning mouth syndrome is caused by an underlying medical condition. In these cases, it's called secondary burning mouth syndrome.

Underlying problems that may be linked to secondary burning mouth syndrome include:

• Dry mouth (xerostomia), which can be caused by various medications, health problems, problems with salivary gland function or the side effects of cancer treatment
• Other oral conditions, such as a fungal infection of the mouth (oral thrush), an inflammatory condition called oral lichen planus or a condition called geographic tongue that gives the tongue a maplike appearance
• Nutritional deficiencies, such as a lack of iron, zinc, folate (vitamin B-9), thiamin (vitamin B-1), riboflavin (vitamin B-2), pyridoxine (vitamin B-6) and cobalamin (vitamin B-12)
• Allergies or reactions to foods, food flavorings, other food additives, fragrances, dyes or dental-work substances
• Reflux of stomach acid (gastroesophageal reflux disease, or GERD) that enters your mouth from your stomach
• Certain medications, particularly high blood pressure medications
• Oral habits, such as tongue thrusting, biting the tip of the tongue and teeth grinding (bruxism)
• Endocrine disorders, such as diabetes or underactive thyroid (hypothyroidism)
• Excessive mouth irritation, which may result from overbrushing your tongue, using abrasive toothpastes, overusing mouthwashes or having too many acidic drinks
• Psychological factors, such as anxiety, depression or stress

Wearing dentures, even if they don't fit well and cause irritation, doesn't generally cause burning mouth syndrome, but dentures can make symptoms worse.