What are the possible causes and treatments for itchiness at the tongue in a patient with unknown medical history and demographics?

Tongue Itchiness: Causes and Management

Tongue itchiness is most commonly caused by oral allergy syndrome (OAS) in patients with seasonal allergic rhinitis, burning mouth syndrome (BMS), or fungiform papillary glossitis in atopic individuals, and requires immediate evaluation for potential allergic reactions while addressing underlying conditions. 1, 2, 3

Immediate Assessment for Allergic Causes

Oral Allergy Syndrome (OAS)

• OAS presents with pruritus of the oral mucosa, particularly the posterior tongue, occurring immediately after eating certain raw fruits, vegetables, spices, or nuts 1
• Strongly associated with seasonal allergic rhinitis (hay fever) 1
• Symptoms include tingling on the tongue, itching in the throat, and facial itching within seconds to minutes of food contact 4, 1
• Cooking offending foods typically eliminates symptoms, as heat denatures the allergenic proteins 1
• Consider referral to primary care or allergy specialist due to rare possibility of progression to anaphylaxis 1

Insect Sting Reactions

• Tongue swelling with itching can indicate systemic allergic reaction requiring immediate epinephrine administration 2
• Upper airway obstruction from tongue or throat swelling represents life-threatening emergency 2

Chronic Tongue Itching Conditions

Burning Mouth Syndrome (BMS)

• BMS affects predominantly peri- and post-menopausal women, presenting with burning, stinging, or itchy sensations of the tongue (especially bilateral tip), lips, palate, or buccal mucosa 2
• Oral mucosa appears completely normal on examination 2
• Continuous symptoms in most instances, with severity ranging from mild to severe 2
• Secondary causes must be excluded: oral candidiasis, mucosal lesions, iron deficiency anemia, vitamin B12 deficiency, folate deficiency, autoimmune disorders, and medication side effects 2, 5
• Treatment includes reassurance, education, cognitive behavioral therapy (CBT), and potentially gabapentin or alpha-lipoic acid for neuropathic pain 2, 5

Fungiform Papillary Glossitis (Atopic Tongue)

• Atopic individuals (those with asthma, eczema, or hay fever) have significantly increased likelihood of inflamed fungiform papillae causing tongue sensitivity and itching 3
• Presents with irritation from hot foods and certain specific foods 3
• Examination reveals inflamed fungiform papillae on tongue surface 3
• More common than recognized in atopic populations 3

Geographic Tongue and Related Conditions

Geographic Tongue (Benign Migratory Glossitis)

• Represents localized type of psoriasis inversa 6
• Does not require treatment in most cases 5
• May be associated with burning mouth syndrome and other oral comorbidities 6
• 70% of patients present with Type I geographic tongue, though severe forms can occur 6

Median Rhomboid Glossitis

• Usually associated with candidal infection 5
• Responds to topical antifungal therapy 5

Nutritional Deficiency-Related Glossitis

Atrophic Glossitis

• Linked to iron deficiency (most common systemic cause of pruritus), folic acid deficiency, vitamin B12 deficiency, riboflavin deficiency, or niacin deficiency 5, 7
• Iron deficiency accounts for 25% of all patients with pruritus due to systemic disease 7
• Resolves with correction of underlying nutritional deficiency 5
• Check ferritin levels, but note that ferritin is an acute-phase protein and may be falsely elevated; verify with serum iron and total iron binding capacity if deficiency suspected 7

Systemic Causes Requiring Investigation

Hematological Conditions

• Polycythemia vera presents with characteristic aquagenic pruritus and can affect oral mucosa 7, 2
• Lymphoma may present with itching (particularly nocturnal) associated with weight loss, fevers, and night sweats 8
• Full blood count and ferritin levels should be ordered in all patients with chronic generalized pruritus 7

Other Systemic Causes

• Chronic kidney disease (uremia) 7
• Cholestatic liver disease (check liver function tests) 7
• Drug-induced pruritus from medications 2

Diagnostic Workup

Essential Initial Testing

• Full blood count and ferritin levels 7
• Liver function tests 7
• Urea and electrolytes 7
• Serum iron and total iron binding capacity if iron deficiency suspected 7

Allergy Testing

• Skin prick testing (SPT) and specific IgE testing (CAP-FEIA) for suspected food allergens in OAS 4, 2
• Testing for seasonal allergens if allergic rhinitis suspected 2, 1

Treatment Algorithm

For OAS

1. Identify and avoid raw forms of offending foods 1
2. Advise cooking foods to denature allergenic proteins 1
3. Consider oral second-generation antihistamines (fexofenadine 180 mg or loratadine 10 mg) for associated allergic rhinitis 2
4. Prescribe epinephrine auto-injector if risk of progression to anaphylaxis 2

For BMS

1. Exclude secondary causes through appropriate testing 2
2. Provide reassurance that condition will not worsen 2
3. Consider gabapentin 300 mg for neuropathic component 2
4. Offer cognitive behavioral therapy 2
5. Trial alpha-lipoic acid in combination with gabapentin 2

For Atopic Tongue/Fungiform Papillary Glossitis

1. Manage underlying atopic conditions (asthma, eczema, allergic rhinitis) 3
2. Avoid known food triggers 3
3. Consider topical corticosteroids for severe inflammation 3

For Nutritional Deficiency

1. Replace iron, vitamin B12, folate, or other identified deficiencies 5, 7
2. Iron replacement often leads to complete cessation of pruritus shortly after starting therapy 7

Critical Pitfalls to Avoid

• Do not dismiss tongue itching in patients with known allergies, as it may herald progression to anaphylaxis 2, 1
• Ferritin levels may be falsely elevated as an acute-phase protein; always verify iron status with serum iron and TIBC 7
• Do not prescribe long-term sedative antihistamines except in palliative care due to dementia risk 7
• Ensure examination of tongue reveals normal mucosa in BMS; any visible lesions suggest alternative diagnosis 2
• Consider malignancy in older patients with tobacco/alcohol use presenting with persistent tongue symptoms 2