Understanding Mouth Sores: Types, Causes, Treatments, and When to Seek Care

Mouth sores (oral ulcers) are common, usually benign, but can signal systemic issues. Here's how to identify, treat, and know when to seek care.

Common Types

Type	Appearance	Cause/Trigger	Contagious?
Canker sore (aphthous ulcer)	Round/oval, white/yellow center, red halo. Inside lips, cheeks, tongue.	Stress, trauma (biting), acidic foods, nutrient deficiency (B12, iron, folate), hormonal shifts, SLS in toothpaste	No
Cold sore (HSV-1)	Clustered fluid-filled blisters → crust. Lip border, outside mouth.	Herpes simplex virus reactivation (stress, sun, illness, immune dip)	Yes (viral shedding)
Hand, Foot & Mouth (Coxsackie)	Red spots/blisters on hands, feet, buttocks + mouth ulcers	Enterovirus. Common in kids <5	Yes (fecal-oral, respiratory)
Oral thrush (Candida)	White plaques (scrape off → red base). Tongue, cheeks, palate	Antibiotics, steroids, diabetes, immunosuppression, dry mouth	Rarely
Lichen planus	White lace-like patches, erosions. Chronic autoimmune	Immune-mediated; trigger often unknown	No

Treatment by Type

• Canker sores: Saltwater rinse, topical steroid (triamcinolone paste), benzocaine, sucralfate slurry. Heal 7–14 days.
• Cold sores: Oral antiviral (valacyclovir 2g BID x1 day at prodrome) or topical (docosanol, penciclovir). Suppressive therapy if frequent.
• HFMD: Supportive: fluids, pain control (acetaminophen), avoid acidic foods.
• Thrush: Antifungal (nystatin swish/swallow, fluconazole). Address underlying cause.
• Lichen planus: Topical steroids, calcineurin inhibitors; specialist follow-up.

When to See a Clinician

• Sore >2 weeks without healing
• Recurrent (>3–4/year) or unusually large/painful
• Accompanied by fever, weight loss, swallowing difficulty, skin rash, joint pain
• Immunocompromised
• Suspicion of oral cancer (indurated, fixed, non-healing, unilateral)

Prevention

• SLS-free toothpaste
• Soft-bristle brush; gentle technique
• Manage stress, sleep, nutrition (B-complex, iron, zinc)
• Avoid known trigger foods
• Good oral hygiene; regular dental exams

Most mouth sores are self-limited. Persistent or atypical ones deserve evaluation—early oral cancer detection saves lives.