What causes lip burning sensation?

What Causes Lip Burning Sensation

Lip burning is most commonly caused by primary burning mouth syndrome (BMS)—a peripheral nerve fiber disorder with central nervous system changes—or by secondary causes including oral candidiasis, nutritional deficiencies (vitamin B12, iron, folate), autoimmune diseases, medications, mucosal lesions, and local irritants. 1, 2

Primary Burning Mouth Syndrome

Primary BMS should be considered a disorder of peripheral nerve fibers with central nervous system changes, predominantly affecting peri- and post-menopausal women. 1 The lips are the third most common site involved in BMS, often occurring alongside tongue and palate involvement. 3

Clinical Characteristics

• Continuous burning, stinging, or itchy sensation affecting the lips bilaterally, with completely normal-appearing oral mucosa on examination. 1
• Associated symptoms include dry mouth, abnormal taste (often metallic), depression, and significantly reduced quality of life. 1, 4
• Tongue biopsies demonstrate significantly lower density of epithelial nerve fibers compared to controls, supporting a neuropathic origin. 1, 4
• Pain severity ranges from mild to severe with continuous timing; eating may aggravate symptoms in some patients while relieving them in others. 2

Pathophysiology

• Neurophysiological testing, biopsies, and functional MRI confirm this is a disorder of altered sensory processing following small fiber neuropathic changes. 1, 4
• Quantitative sensory testing reveals significantly higher sensory thresholds in BMS patients compared to controls. 4

Secondary Causes That Must Be Excluded

Before diagnosing primary BMS, you must systematically exclude all secondary causes through targeted history, examination, and laboratory testing. 1, 2

Infectious Causes

• Oral candidiasis causes burning mouth symptoms; diagnose by scraping and KOH preparation. 1

Nutritional Deficiencies

• Vitamin B12 deficiency is a well-established cause requiring serum B12 measurement. 1
• Iron deficiency anemia frequently presents with burning tongue; check ferritin, serum iron, and TIBC. 1
• Complete blood count with differential identifies anemia as a common cause of oral burning. 1

Mucosal Lesions

• Traumatic ulceration from sharp edges of residual roots/crowns, thermal burns, or chemical injury (strong acid or alkali) can cause burning symptoms. 5, 1
• Thorough oral examination to identify any mucosal abnormalities is mandatory. 1

Autoimmune Diseases

• Sjögren's syndrome and sicca syndrome can manifest with oral burning and must be excluded. 1

Endocrine Disorders

• Thyroid disorders, particularly hyperthyroidism, can cause tongue erythema and burning. 1

Medication Side Effects

• Various pharmacological agents can cause oral burning as a side effect. 1

Neuropathic Pain Conditions

• Post-traumatic trigeminal neuropathic pain and post-herpetic neuralgia can cause burning mouth symptoms. 1
• Post-traumatic trigeminal neuropathic pain presents as continuous burning, tingling pain within 3-6 months of dental procedures or facial trauma. 2

Infectious Diseases

• Scarlet fever and Kawasaki disease can present with oral burning symptoms. 1
• Kawasaki disease specifically presents with erythema, lip cracking, fissuring, peeling, and bleeding of the lips. 5

Local Irritants

• Poor oral hygiene or irritating oral care products containing alcohol should be excluded. 2

Diagnostic Algorithm

Step 1: Detailed Clinical History

Focus on onset timing, medication use, systemic diseases, dental procedures, and trauma history. 1, 2

Step 2: Thorough Oral Examination

Inspect oral mucosa for lesions, candidiasis, or traumatic factors; test for allodynia; palpate temporomandibular joints. 1, 2

Step 3: Essential Laboratory Workup

• Complete blood count with differential 1
• Vitamin B12 levels 1
• Iron studies (ferritin, serum iron, TIBC) 1
• Folate, glucose, thyroid function tests 2
• Inflammatory markers (ESR/CRP) if patient is over 50 years old to exclude giant cell arteritis 2

Step 4: Additional Testing When Indicated

• Oral swab for candidiasis if mucosal changes are present 2
• Qualitative sensory testing if neuropathic etiology is suspected 1
• Biopsy if mucosal abnormalities are present or diagnosis is uncertain 1
• MRI of brain and trigeminal nerve is mandatory to exclude structural lesions, tumors, or nerve compression 2

Critical Red Flags Requiring Urgent Evaluation

Giant cell arteritis must be distinguished, especially in patients over 50 years old, presenting with temporal artery tenderness, jaw claudication, visual symptoms, and elevated inflammatory markers. 2

Cancer can present as progressive neuropathic pain with burning quality; MRI is mandatory to exclude structural lesions. 2

Common Pitfalls to Avoid

• Failing to exclude secondary causes before diagnosing primary BMS leads to missed treatable conditions. 2
• Inadequate reassurance about BMS prognosis increases patient anxiety and worsens quality of life. 2
• Missing giant cell arteritis in patients over 50 years can result in permanent vision loss. 2
• Performing invasive procedures without objective findings should be avoided. 2

Burning Lips Syndrome: A Distinct Entity

A distinct diagnostic entity called "burning lips syndrome" has been proposed, characterized by burning sensation limited to the lips, smooth and pale labial mucosa, and nonfunctional minor salivary glands of the lips. 6 This condition affects men as often as women, typically occurring between 50 and 70 years of age, and may respond favorably to topical corticosteroids. 6

Treatment Approach for Primary BMS

First-line treatment includes reassurance, patient education, and cognitive behavioral therapy. 2

Pharmacological treatment: Gabapentin 300mg at bedtime, titrating to 900-3600mg daily in divided doses. 2

Alternative agents include amitriptyline, alpha lipoic acid combined with gabapentin, or topical clonazepam. 2

Symptomatic management includes saliva substitutes for dry mouth, avoiding irritating oral products, and bland oral rinses for taste disturbances. 2

Patients should be informed about the chronic nature of BMS; refer to pain specialists or neurologists if inadequate response after 4-6 weeks. 2