What causes a wavy tongue and how is it treated?

Wavy Tongue (Scalloped Tongue/Crenated Tongue)

What It Is and Primary Causes

A wavy or scalloped tongue (also called crenated tongue) presents with indentations along the lateral borders that match the pattern of adjacent teeth, creating a wave-like appearance. This finding is typically benign and most commonly results from chronic tongue pressure against the teeth, often due to macroglossia (enlarged tongue), parafunctional habits like tongue thrusting, or chronic tongue edema. 1

Most Common Underlying Causes:

• Macroglossia (enlarged tongue) from hypothyroidism, amyloidosis, acromegaly, or Down syndrome creates persistent pressure against teeth 1
• Chronic tongue edema from sleep apnea, where the tongue swells and presses against teeth during sleep 1
• Parafunctional habits including tongue thrusting, bruxism, or chronic tongue pressing against teeth during stress 1
• Temporomandibular joint disorders that alter tongue positioning 1
• Dehydration or electrolyte imbalances causing tissue changes 1

When to Worry: Red Flags Requiring Urgent Evaluation

While scalloped tongue is usually benign, certain presentations demand immediate attention:

• New onset with voice changes (dysphonia) requires laryngoscopy within 4 weeks or immediately if serious underlying cause suspected, as this could indicate tongue base mass, lingual thyroid enlargement, or other pathology 2
• Progressive tongue enlargement with dysphagia, respiratory distress, or stridor requires urgent evaluation for airway compromise 2
• Associated neck mass mandates immediate laryngoscopy to exclude malignancy 3, 4
• Tongue lesions, ulcerations, or growths require biopsy to differentiate benign lesions from premalignant leukoplakia or squamous cell carcinoma 1

Diagnostic Approach

Initial Assessment:

• History: Duration of symptoms, associated dysphagia, voice changes, sleep disturbances (snoring, witnessed apneas), thyroid symptoms, medication use 1
• Physical examination: Tongue size relative to oral cavity, presence of lesions or color changes, dental occlusion, assessment for lymphadenopathy 1
• Thyroid function testing if macroglossia suspected (TSH, free T4) 1

When to Escalate:

• Laryngoscopy indicated if any voice changes persist beyond 4 weeks, or immediately if serious underlying cause suspected (recent surgery, tobacco use, concomitant neck mass, respiratory symptoms) 2, 3
• Sleep study if obstructive sleep apnea suspected based on snoring, witnessed apneas, daytime somnolence 1
• Referral to oral and maxillofacial surgery or ENT for tongue lesions of unclear etiology or progressive macroglossia 1

Treatment Based on Underlying Cause

For Benign Scalloped Tongue Without Underlying Pathology:

• Reassurance and observation as isolated scalloped tongue without symptoms requires no treatment 1
• Behavioral modification for tongue thrusting or parafunctional habits 1
• Hydration optimization if dehydration contributing 1

For Specific Underlying Conditions:

• Hypothyroidism: Thyroid hormone replacement resolves macroglossia and scalloping 1
• Sleep apnea: CPAP therapy or other airway management reduces tongue edema 1
• TMJ disorders: Dental referral for occlusal adjustment or splint therapy 1

For Associated Tongue Conditions Requiring Treatment:

• Median rhomboid glossitis (candidal infection): Topical antifungals 1
• Atrophic glossitis (nutritional deficiency): Correction of underlying iron, folate, B12, riboflavin, or niacin deficiency 1
• Oral hairy leukoplakia (Epstein-Barr virus in immunocompromised): Oral antivirals 1

Critical Pitfalls to Avoid

• Do not dismiss new tongue changes with voice alterations without laryngoscopy, as this can delay diagnosis of laryngeal or tongue base malignancy with worse outcomes 2, 4
• Do not assume all scalloped tongue is benign in smokers or those with tobacco/alcohol use, who have 2-3 fold increased cancer risk and require lower threshold for evaluation 4
• Do not overlook progressive macroglossia which may indicate serious systemic disease (amyloidosis, acromegaly) or airway compromise risk 1
• Do not perform imaging (CT/MRI) before visualizing the tongue and larynx if voice complaints present, as direct visualization is the appropriate first step 2