What is the next step in treatment for a patient on Lamictal (lamotrigine) experiencing a burning sensation in the mouth?

Immediate Action: Discontinue Lamictal and Evaluate for Drug Hypersensitivity

Stop lamotrigine immediately and evaluate for Stevens-Johnson syndrome (SJS) or other serious hypersensitivity reactions, as oral burning can be an early warning sign of severe mucocutaneous reactions. 1

Critical Initial Assessment

Rule Out Drug-Related Hypersensitivity (First Priority)

• Examine for any skin rash, blistering, or mucosal lesions anywhere on the body, as lamotrigine carries significant risk for SJS/TEN, particularly within the first 8 weeks but can occur at any time 1
• Check for fever, lymphadenopathy, or systemic symptoms that would indicate DRESS syndrome 1
• If any rash, mucosal lesions, or systemic symptoms are present: this is a medical emergency requiring immediate hospitalization 1
• Even without visible lesions, oral burning in a patient on lamotrigine warrants drug discontinuation given the potential severity of delayed hypersensitivity reactions 1

Examine Oral Mucosa Thoroughly

• Inspect for candidiasis (white plaques that scrape off), traumatic ulceration, erythema, or any mucosal abnormalities that would indicate secondary causes rather than primary burning mouth syndrome 2
• Check for signs of xerostomia (dry mouth), which commonly accompanies burning sensations 2
• Assess tongue for erythema, coating, or geographic patterns 2

Diagnostic Workup

Laboratory Testing (Order Immediately)

• Complete blood count with differential to identify anemia, which commonly causes oral burning 2
• Vitamin B12 level as deficiency is a well-established cause of secondary burning mouth syndrome 2
• Iron studies (ferritin, serum iron, TIBC) as iron deficiency frequently presents with burning tongue 2
• Thyroid function tests to exclude hyperthyroidism, which can cause tongue erythema and burning 2

Additional Evaluation if Initial Workup Negative

• Consider screening for autoimmune conditions (Sjögren's syndrome, sicca syndrome) if dry mouth is prominent 2
• Oral candidiasis testing via scraping and KOH preparation if white lesions or coating present 2

Management Algorithm

If Hypersensitivity Reaction Suspected

• Discontinue lamotrigine permanently - do not rechallenge 1
• Refer to emergency department if any mucosal lesions, rash, or systemic symptoms present 1
• Coordinate with prescribing psychiatrist/neurologist for alternative mood stabilizer or anticonvulsant 1

If Secondary Cause Identified

• Treat nutritional deficiencies (B12, iron) with appropriate supplementation 2
• Treat candidiasis with antifungal therapy if identified 2
• Address thyroid dysfunction or autoimmune conditions as appropriate 2

If Primary Burning Mouth Syndrome Diagnosed (After Exclusion of All Secondary Causes)

Symptomatic Management:

• Gabapentin as first-line pharmacological treatment, which reduces burning sensation in 50% of patients 3
• Consider alpha lipoic acid combined with gabapentin for superior outcomes compared to monotherapy 3
• Cognitive behavioral therapy as primary non-pharmacological intervention to address psychological components 3

Supportive Care:

• Viscous lidocaine 2% for temporary relief, 15 mL held in mouth for 1-2 minutes before spitting 4
• Soft toothbrush and alcohol-free mouthwash to prevent irritation 4
• Avoid crunchy, spicy, acidic, or hot foods that exacerbate discomfort 3

Red Flags Requiring Urgent Referral

• Unilateral pain with induration or non-healing ulceration, especially in patients over 40 with tobacco/alcohol use - requires biopsy to exclude malignancy 4
• Progressive neuropathic pain that worsens over time may indicate underlying cancer 5
• Persistent symptoms after 2 weeks of appropriate treatment warrant specialist reevaluation 4

Common Pitfalls to Avoid

• Do not assume all oral burning is benign - lamotrigine-associated mucosal reactions can be life-threatening 1
• Do not continue lamotrigine while "monitoring" symptoms - the risk of progression to SJS/TEN is too high 1
• Inadequate reassurance about the chronic nature of primary BMS increases patient anxiety and should be avoided 3
• Do not use petroleum-based products chronically on oral mucosa as they promote dehydration 4