What are the causes of a burning sensation in the mouth?

Causes of Burning Mouth Sensation

Burning mouth syndrome (BMS) is primarily a neuropathic disorder affecting peripheral nerve fibers with central brain changes, predominantly seen in peri- and post-menopausal women, but secondary causes including oral candidiasis, mucosal lesions, hematological disorders, autoimmune disorders, and medication side effects must be systematically excluded before diagnosing primary BMS. 1

Primary (Idiopathic) Burning Mouth Syndrome

Primary BMS represents a disorder of peripheral nerve fibers with central nervous system changes, confirmed through neurophysiological testing, biopsies, and functional MRI. 1 This condition manifests as:

• Continuous burning, stinging, or itchy sensation most commonly affecting the tongue tip bilaterally, lips, palate, and buccal mucosa 1
• Normal-appearing oral mucosa on examination—the absence of visible lesions is a defining characteristic 1
• Associated symptoms including dry mouth, abnormal taste (metallic or diminished), depression, and poor quality of life 1, 2
• Significantly lower density of epithelial nerve fibers in tongue biopsies compared to controls, supporting the neuropathic origin 3

Secondary Causes (Must Be Excluded First)

Local Oral Factors

• Oral candidiasis—fungal infection that can cause burning, diagnosed by scraping and KOH preparation 1, 4
• Mucosal lesions—including traumatic ulceration from sharp edges of residual roots/crowns, thermal burns, or chemical injury 1
• Denture-related lesions and mechanical irritation 5
• Contact stomatitis from hypersensitivity reactions to dental materials or oral care products 6, 5

Hematological and Nutritional Deficiencies

• Hematinic deficiencies—iron, folate, and vitamin B complex deficiencies are common culprits 1, 7
• Nutritional deficiencies that must be screened through laboratory testing 6, 5

Systemic and Autoimmune Disorders

• Autoimmune diseases—various autoimmune conditions can manifest with oral burning 1, 2
• Diabetes mellitus—systemic disease associated with burning mouth symptoms 5
• Thyroid disorders, particularly hyperthyroidism, can cause tongue erythema and burning 4
• Sjögren's syndrome and sicca syndrome—distinct from typical BMS, with abrupt onset of dry mouth 1

Hormonal Changes

• Menopause-related hormonal disturbances—onset typically occurs 3-12 years after menopause in women 5, 3
• Higher prevalence in women with more systemic disease 3

Medication Side Effects

• Pharmacological side effects from various medications can cause oral burning 1, 5
• Xerostomia-inducing medications that reduce saliva production 5

Infectious Causes

• Scarlet fever (Group A Streptococcal infection)—presents with "strawberry tongue" initially white-coated then bright red, accompanied by fever and rash, more common in children aged 5-15 years 4
• Kawasaki disease—presents with red, swollen "strawberry tongue," primarily affects children, associated with fever and can lead to cardiac complications if untreated 4

Neuropathic and Post-Traumatic Causes

• Post-traumatic trigeminal neuropathic pain—continuous burning or tingling within 3-6 months of dental procedure or trauma, with possible allodynia or sensory changes 1
• Post-herpetic neuralgia—burning, tingling pain at site of herpes zoster, with allodynia and hyperalgesia 1

Behavioral and Psychological Factors

• Oral habits—tongue thrusting and bruxism can contribute to burning sensations 7
• Depression and anxiety—frequently co-exist with BMS, though they don't fully explain the condition 3, 7

Diagnostic Algorithm

The diagnosis of BMS is one of exclusion—all secondary causes must be ruled out before establishing primary BMS. 6, 5

1. Detailed clinical history focusing on onset timing (relation to menopause), medication use, systemic diseases, and dental procedures 1, 2
2. Thorough oral examination to identify mucosal lesions, candidiasis, or traumatic factors 1
3. Laboratory screening including complete blood count, iron studies, folate, vitamin B12, glucose, and thyroid function 6, 5
4. Qualitative sensory testing if neuropathic etiology suspected 1
5. Consider biopsy if mucosal abnormalities present or diagnosis uncertain 1

Critical Pitfall to Avoid

Professional delay in diagnosing, referring, and appropriately managing BMS patients occurs frequently—do not dismiss patients with normal-appearing mucosa without systematic exclusion of secondary causes. 5 Multiple concurrent causes may be identified in more than one-third of patients, requiring comprehensive evaluation. 5