What's This Spot in My Mouth?

Common Mouth Sores and What They Look Like

Canker Sores

A canker sore (aphthous ulcer) is a small, round sore inside the mouth with a white or yellow center and a red border. Canker sores show up on the inner lip, inner cheek, tongue, or floor of the mouth. They are not contagious. Most heal on their own in one to two weeks. Triggers include stress, acidic foods, a small bite injury, and sometimes a vitamin deficiency.

If a canker sore is larger than a pencil eraser, lasts longer than two weeks, or keeps coming back, have it checked. Recurring canker sores can be linked to celiac disease, Crohn’s disease, or Behcet’s disease. A dentist with oral medicine training can tell the difference and find the cause.

How to Treat Canker Sores

Most canker sores heal without treatment. To ease the pain and help them heal faster:

• Rinse with warm salt water (half a teaspoon of salt in a cup of water) several times a day.
• Apply an over-the-counter paste with benzocaine (Orabase, Orajel) directly to the sore.
• Avoid spicy, acidic, or rough foods until the sore closes.
• Switch to a toothpaste without sodium lauryl sulfate (SLS), which can trigger canker sores in some people.
• Take ibuprofen or acetaminophen for pain if needed.

For large or frequent canker sores, a dentist may prescribe a steroid mouth rinse or a prescription-strength topical paste. In our office, Dr. Henley evaluates recurring mouth ulcers as part of a thorough oral medicine workup to look for an underlying cause before treating the symptoms alone.

Mouth Sores: Types and What to Watch For

Most mouth sores fall into a few categories. Knowing the differences helps you decide what needs attention:

• Canker sores are painful, shallow ulcers inside the mouth. Not contagious.
• Cold sores (fever blisters) are clusters of small blisters on or near the lip caused by the herpes simplex virus. Contagious until fully healed.
• Oral thrush produces creamy white patches that can be wiped off. It is a yeast infection, not a virus.
• Leukoplakia is a white patch that does not wipe off and has no obvious cause. It is biopsied because some patches contain early cell changes.
• Oral lichen planus appears as lacy white lines, often on both inner cheeks, sometimes with red or raw areas.
• Oral cancer can look like a sore, lump, or patch that does not heal in two to three weeks. A biopsy is the only way to rule it out.

Use the Mouth Spot Checker above to narrow down what your spot might be, then schedule an exam if anything concerns you.

Mouth Sore Treatment

Treatment depends on the cause. A sore that has lasted more than two weeks, is growing, bleeds easily, or is numb should be examined by a dentist. Here is a general guide:

• Canker sores: Salt-water rinses, OTC numbing gels, SLS-free toothpaste. Prescription rinses for severe or recurring cases.
• Cold sores: Over-the-counter antiviral cream (docosanol/Abreva) or a prescription antiviral (valacyclovir) started at the first tingle.
• Thrush: Antifungal rinse or lozenge prescribed by your dentist. Treating the cause (adjusting dentures, managing dry mouth, switching inhalers) prevents it from coming back.
• White patches or red patches: A biopsy determines the next step. Early detection is the goal of every oral cancer screening.
• Recurring ulcers with other symptoms: Blood work and a full oral medicine evaluation to check for autoimmune, nutritional, or systemic causes.

Viral Infections in the Mouth

Several viruses cause sores, blisters, or ulcers inside the mouth:

• Herpes simplex (HSV-1): Causes cold sores on the lips and, inside the mouth, painful blisters on the gums and hard palate. Recurrences are common, often triggered by sun, stress, or illness.
• Hand, foot, and mouth disease (Coxsackievirus): Mostly affects young children. Painful sores at the back of the mouth with a rash on the hands and feet.
• Herpangina: Similar to hand, foot, and mouth but limited to the throat and soft palate.
• Shingles (varicella-zoster): Painful blisters on one side of the mouth only, stopping sharply at the midline. Antivirals work best within 72 hours.
• HPV: Low-risk strains cause small, cauliflower-like growths (oral papillomas) that are usually removed and sent to a lab.

Viral mouth infections are diagnosed by their appearance and pattern. Antiviral medications help manage herpes and shingles when started early. If you are unsure whether a mouth sore is viral, bacterial, or something else, a dentist trained in oral medicine can sort it out quickly.

Mouth Infections: When to See a Dentist

Not every spot in the mouth is an infection. But certain signs mean you should call a dentist:

• A sore or lump that has not healed in two weeks
• White or red patches that do not wipe off
• A bump that is growing, firm, or bleeds easily
• Numbness in part of the mouth, lip, or tongue
• Swelling in the neck or under the jaw
• Pain that is getting worse, not better

Dr. Henley includes an oral cancer screening in every exam and has advanced training in diagnosing conditions that general dentists often refer out. Patients in Jacksonville, San Marco, Southside, Mandarin, Riverside, the Beaches, and Ponte Vedra trust this office for second opinions on mouth sores and spots that other providers could not explain.

Common Mouth Diseases at a Glance

Start with the Mouth Spot Checker above to match your symptoms, or browse the full oral conditions library for detailed guides on each condition.