What is the cause of red dots appearing under the tongue?

Red Dots Under the Tongue: Causes and Clinical Approach

Red dots appearing under the tongue most commonly represent normal anatomical structures (lingual varicosities or minor salivary glands), but can also indicate viral infections like hand, foot, and mouth disease (HFMD), or less commonly, systemic conditions requiring urgent evaluation.

Normal Anatomical Variants

The ventral (underside) surface of the tongue contains several structures that can appear as red dots:

• Lingual varicosities: Dilated veins that appear as purple-red dots or tortuous vessels, increasingly common with age and typically benign 1
• Minor salivary glands: Small red or pink papules representing normal glandular tissue on the floor of mouth and ventral tongue 1

These findings require no intervention if asymptomatic and stable over time.

Infectious Causes

Hand, Foot, and Mouth Disease (HFMD)

HFMD is the most common infectious cause of red dots/vesicles under the tongue and oral mucosa, particularly in children but also occurring in adults 2:

• Clinical presentation: Fever (often up to 40°C), painful oral lesions (vesicles that may appear as red dots before rupturing), and characteristic rash on hands/feet 2, 3
• Oral findings: Vesicles and ulcers on tongue (including ventral surface), buccal mucosa, palate, and lips 2
• Diagnosis: Clinical diagnosis is typically sufficient; RT-PCR of vesicle fluid, respiratory samples, or stool can confirm if needed 2
• Management: Supportive care with acetaminophen or NSAIDs for pain/fever; benzydamine hydrochloride oral rinse before eating; white soft paraffin ointment to lips every 2 hours 2, 4

Scarlet Fever

If accompanied by high fever and sandpaper-like rash:

• "Strawberry tongue": Initially white-coated, then bright red with prominent papillae 3
• Associated findings: Sandpaper-textured rash, most common in children aged 5-15 years 3
• Requires: Throat culture or rapid strep test and antibiotic treatment if confirmed 3

Critical Red Flags Requiring Urgent Evaluation

Do not dismiss oral findings if accompanied by systemic symptoms 4, 3:

• Kawasaki disease: Fever ≥5 days, strawberry tongue, polymorphous rash, conjunctival injection, extremity changes, or cervical lymphadenopathy ≥1.5 cm 3

  • Incomplete Kawasaki disease can present with fewer features, particularly in infants <1 year 3
  • Immediate action: Measure ESR and CRP; if ESR ≥40 mm/hr or CRP ≥3 mg/dL, obtain CBC, CMP, urinalysis, and echocardiography 3
  • Untreated Kawasaki disease leads to coronary artery aneurysms in up to 25% of patients 3

• Anaphylaxis: Throat tightness, difficulty breathing, wheezing, weak pulse, dizziness, or widespread hives 4

• Systemic infection: Temperature >100.4°F (>38°C), tachycardia, altered mental status 4

Examination Approach

Perform a systematic oral examination 1:

1. Remove dentures if present
2. Use bright light and tongue depressor (do NOT have patient protrude tongue, as this obscures the oropharynx)
3. Use gauze to grasp and manipulate tongue to inspect lateral and ventral surfaces
4. Palpate floor of mouth and tongue base for masses or ulcers
5. Inspect for asymmetry, ulceration, or suspicious lesions

Document specific characteristics 1:

• Size, number, and distribution of red dots
• Presence of vesicles, ulcers, or bleeding
• Associated symptoms (pain, fever, difficulty swallowing)
• Symmetry versus asymmetry (asymmetry raises concern for malignancy)

When to Refer

Refer to specialist if 1:

• Oral examination is incomplete due to anatomic constraints
• Lesions persist beyond 4 weeks without clear infectious etiology 4
• Asymmetric findings or concern for malignancy
• Systemic symptoms suggesting Kawasaki disease or other serious condition

Common Pitfalls to Avoid

• Do not assume all oral red dots are benign without considering clinical context 2, 4
• Do not dismiss Kawasaki disease because conjunctivitis is absent—incomplete presentations are common, especially in infants 3
• Do not attribute findings solely to antibiotic reaction if patient has prolonged fever—this is a classic missed diagnosis scenario for Kawasaki disease 3
• Do not assume HFMD is only pediatric—adults can develop severe manifestations requiring supportive care 4