Mouth Ulcers: Causes, Symptoms, and Treatment
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Mouth Ulcers?
A dentist, a doctor who cares for the teeth and mouth, or a primary care doctor usually checks and treats mouth ulcers. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What are mouth ulcers?
Mouth ulcers are sores or open lesions in the mouth. They are common and should clear up on their own within a week or 2. Many mouth ulcers are harmless and heal without treatment.
One common kind is the canker sore. It is a small white or gray sore with a red border inside the mouth. Canker sores are not contagious and should not be confused with cold sores. Cold sores appear on the lips or around the mouth. Some disorders that cause mouth ulcers are contagious and can spread to other people.
Symptoms
Symptoms depend on the cause of the ulcer. They may include:
- Open sores in the mouth.
- Pain or discomfort in the mouth.
Causes and who gets it
Mouth ulcers are caused by many disorders. The exact cause of canker sores is uncertain. Most single mouth ulcers are caused by things you can try to avoid, such as:
- Biting the inside of your cheek.
- Badly fitting dentures, braces, rough fillings, or a sharp tooth.
- A food intolerance or allergy.
- Feeling tired, stressed, or anxious.
Sometimes ulcers are triggered by things you cannot always control, such as:
- Hormonal changes, such as during pregnancy.
- Your genes. Some families get mouth ulcers more often.
- A vitamin or mineral shortage, such as low iron, zinc, folic acid, vitamin B, or vitamin D.
- Some medicines, including some NSAIDs (a group of pain medicines), beta blockers, or nicorandil.
- Stopping smoking. People may develop mouth ulcers when they first stop smoking.
Having several mouth ulcers can be a symptom of other health problems, such as hand, foot and mouth disease, oral lichen planus (a condition that causes a white, lacy pattern inside the cheeks), Crohn's disease, celiac disease, or a weakened immune system from a condition like HIV or lupus.
How doctors diagnose it
Most of the time, a health care provider or dentist will look at the ulcer and where it is in the mouth to make the diagnosis. You may need blood tests, or a biopsy of the ulcer, to confirm the cause. A biopsy means a small piece of tissue is taken and tested.
Treatment
The goal of treatment is to relieve symptoms. This can be done by:
- Treating the underlying cause of the ulcer if it is known.
- Gently cleaning your mouth and teeth.
- Rubbing medicines directly on the ulcer, such as antihistamines, antacids, and corticosteroids, that may soothe discomfort.
- Avoiding hot or spicy foods until the ulcer is healed.
Avoiding things that irritate the ulcer should help speed up healing, reduce pain, and reduce the chance of it returning. Helpful steps include using a soft-bristled toothbrush, drinking cool drinks through a straw, and eating softer foods. Do not eat very spicy, salty, or acidic food, or rough, crunchy food. Do not drink very hot or acidic drinks. Do not use toothpaste containing sodium lauryl sulfate.
A pharmacist can recommend a treatment to speed up healing, prevent infection, or reduce pain. Examples are an antimicrobial mouthwash, a painkilling tablet, mouthwash, gel or spray, corticosteroid lozenges, or a salt water mouthwash. You can buy these without a prescription. A dentist or doctor may prescribe stronger medicine for severe, persistent or infected mouth ulcers, such as steroids given as a mouth spray or as tablets that dissolve in the mouth.
When to see a doctor
See a dentist or doctor if your mouth ulcer:
- Lasts longer than 3 weeks.
- Is different from other mouth ulcers you have had before, for example if it is bigger than usual or near the back of your throat.
- Bleeds or becomes more painful and red. This may be a sign of an infection.
- Comes back often, or comes with new symptoms.
You should also see a doctor if you have ulcers anywhere else on your body, such as your skin or genitals, or painful, red or swollen joints. Although most mouth ulcers are harmless, a long-lasting mouth ulcer is sometimes a sign of mouth cancer. It is best to get it checked.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. A direct primary care doctor can look at the ulcer, review your medicines, and refer you to a dentist or another specialist when needed.
Common questions
Are mouth ulcers contagious?
It depends on the cause. Canker sores are not contagious, but some disorders that cause mouth ulcers can spread to other people.
How long do mouth ulcers last?
Most mouth ulcers clear up on their own within a week or 2. See a dentist or doctor if a mouth ulcer lasts longer than 3 weeks.
Can a mouth ulcer be a sign of cancer?
Sometimes. Although most mouth ulcers are harmless, a long-lasting mouth ulcer is sometimes a sign of mouth cancer. Some types of cancer may first appear as a mouth ulcer that does not heal.
Can stress cause mouth ulcers?
Stress may be one trigger. Feeling tired, stressed or anxious is listed as a cause of single mouth ulcers. The exact cause of canker sores is uncertain, but some experts believe that immune system problems, bacteria, or viruses may be involved.
Sources
- MedlinePlus - Mouth ulcers
- NHS - Mouth ulcers
- MouthHealthy (American Dental Association) - Canker Sores
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
