Burning Mouth Syndrome

Burning mouth syndrome (BMS) is a chronic intraoral burning or dysaesthetic sensation recurring daily for more than 2 hours a day over at least 3 months, with normal appearing mucosa and no identifiable medical or dental cause. Prevalence is 1 to 4 percent of the general population, rising to 12 to 18 percent in post-menopausal women, with a female to male ratio of 5 to 7 to 1 and peak age 50 to 70 years.

Primary BMS is a neuropathic disorder involving peripheral small fibre degeneration of oral epithelium, central dysregulation of pain pathways (reduced dopaminergic inhibition in the basal ganglia), and hormonal changes.

Secondary burning mouth arises from identifiable causes: candidiasis, nutritional deficiency (iron, B12, folate, zinc), diabetes, xerostomia, contact allergy, lichen planus, ill fitting dentures, drugs (angiotensin converting enzyme inhibitors), and psychological conditions (anxiety, depression, cancerphobia). Spontaneous remission occurs in about 3 percent of patients per year, and symptoms usually persist for 3 to 7 years.

• Continuous burning, scalding or tingling pain, usually bilateral, most often at the tongue tip and lateral borders, then lips, hard palate and buccal mucosa; low in the morning, rising during the day with a peak in the evening.
• Often accompanied by dry mouth (xerostomia), altered taste (metallic or bitter, dysgeusia), thirst.
• Relief with eating, drinking and distraction; worsening with stress, fatigue and acidic foods.
• Normal oral mucosa on examination; no sleep disturbance due to pain (pain does not wake the patient).
• Comorbid: anxiety, depression, insomnia, fibromyalgia, irritable bowel syndrome.
• Red flags: visible lesion, ulceration, white or red patch, lymphadenopathy, unilateral symptoms with sensory loss, weight loss, jaw claudication.

• Diagnosis by exclusion: typical history, normal mucosa, and exclusion of local and systemic causes.
• Full oral and dental examination, including dentures, parafunctional habits, and salivary flow (unstimulated flow below 0.1 mL/min indicates hyposalivation).
• Swab or oral rinse for Candida; patch testing for contact allergy.
• Blood tests: full blood count, ferritin, vitamin B12, folate, zinc, fasting glucose or HbA1c, thyroid function, and, if relevant, anti-nuclear antibody, anti-Ro and anti-La antibodies (Sjogren syndrome).
• Medication review (ACE inhibitors, antiretrovirals, antidepressants with xerostomia).
• Questionnaires for pain (visual analogue scale), anxiety and depression (Hospital Anxiety and Depression Scale).
• Quantitative sensory testing or biopsy only in research or atypical cases.
• Exclude candidiasis, geographic tongue, lichen planus, atrophic glossitis, Sjogren syndrome, diabetes, and trigeminal neuropathy.

• Treat secondary causes: candidiasis (miconazole oral gel 20 mg/g, 2.5 mL four times daily for 14 days, or fluconazole 50 mg daily for 7 to 14 days), deficiencies (ferrous sulfate 200 mg three times daily; hydroxocobalamin 1 mg intramuscularly alternate days for 2 weeks then every 3 months; folic acid 5 mg daily for 4 months), diabetes control, denture adjustment, drug change.
• Education, reassurance, and behaviour measures: avoid irritants (alcohol containing mouthwashes, spicy and acidic foods, tobacco), keep hydrated, use sugar free gum, and stress reduction.
• Topical clonazepam: 0.5 mg tablet sucked for 3 minutes and then spat out, 3 times daily for 14 days to 3 months (or a 1 mg tablet dissolved in 5 mL water as a rinse); avoid swallowing to limit sedation; monitor for drowsiness; this is the best evidenced first line therapy.
• Alpha lipoic acid 600 mg orally once daily for 2 months (200 mg three times daily) is an alternative; monitor for gastrointestinal upset.
• Capsaicin 0.025 percent rinse (0.5 mL of 0.025 percent cream or a 0.02 percent rinse), swished for 1 minute 3 times daily, for 1 to 2 months; initial worsening of burning limits use.
• Systemic neuromodulators: amitriptyline 10 mg orally at night increased by 10 mg weekly to 25 to 75 mg; nortriptyline 10 mg increased to 50 mg at night; gabapentin 100 mg three times daily titrated every 3 days to 300 mg three times daily (maximum 1800 mg daily); duloxetine 30 mg once daily increased to 60 mg after 1 week; low dose clonazepam 0.5 mg orally at night may also be used. Review at 4 to 8 weeks and continue for 3 to 6 months if effective.
• Artificial saliva or pilocarpine 5 mg orally three times daily for dry mouth.
• Cognitive behavioural therapy for 8 to 12 sessions reduces pain scores.
• Photobiomodulation (low level laser) at 2 to 3 sessions per week for 10 sessions is used where available.
• Follow up: 4 to 6 weeks after starting treatment, then every 3 months.
• Counselling: the condition is not dangerous, not an indication of cancer, but can persist for years; set realistic goals.