Mouth Sores: Causes, Symptoms, and Treatment
Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Mouth Sores?
A dentist or a primary care doctor usually checks mouth sores. An ear, nose, and throat doctor, who treats problems of the mouth and throat, can help when a sore does not go away. 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 sores?
Mouth sores, also called mouth ulcers, are sores or open lesions in the mouth. Many mouth ulcers are harmless and heal without treatment. Some types of cancer may first appear as a mouth ulcer that does not heal.
Symptoms
Symptoms vary, based on the cause of the mouth ulcer. They may include:
- Open sores in the mouth.
- Pain or discomfort in the mouth.
Canker sores are small, round sores in the mouth. They can be on the inside of the cheek, under the tongue, or in the back of the throat. They usually have a red edge and a gray center, and they can be quite painful.
Cold sores, also called fever blisters, are small, painful blisters from the herpes simplex virus.
Before blisters appear, a person may have a sore throat, fever, swollen glands in the face or neck, or painful swallowing.
Causes and who gets it
Mouth ulcers are caused by many disorders. These include canker sores, herpes simplex (fever blisters), and oral cancer.
Canker sores are not the same as cold sores, which are caused by herpes simplex. Canker sores are not contagious. They may be triggered by stress, food allergies, lack of vitamins and minerals, hormonal changes, or menstrual periods. They may also happen with a viral infection. In some cases the cause is unknown.
Oral herpes is usually caused by the herpes simplex virus type 1 (HSV-1). Most people in the United States are infected with this virus by age 20. After the first infection, the virus becomes dormant, which means inactive, in nerve tissue in the face. Sometimes it later reactivates and causes cold sores.
You can catch it by touching an open sore or something that touched the virus, such as razors, towels, or dishes.
How doctors diagnose it
Most of the time, your 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, which means testing a sample of it, to confirm the cause. A provider can diagnose oral herpes by looking at your mouth area. Sometimes a sample of the sore is sent to a lab.
Treatment
The goal of treatment is to relieve symptoms. This can be done by:
- Treating the cause of the ulcer if it is known.
- Gently cleaning your mouth and teeth.
- Rubbing medicines such as antihistamines, antacids, and corticosteroids directly on the ulcer. They may soothe discomfort.
- Avoiding hot or spicy foods until the ulcer is healed.
In most cases, canker sores go away by themselves. Some ointments, creams, or rinses may help with the pain.
Oral herpes symptoms go away on their own in 1 to 2 weeks. A provider can prescribe antiviral medicine, such as acyclovir, famciclovir, or valacyclovir. It can reduce pain and make symptoms go away sooner. These medicines work best if you take them when you have warning signs, before any blisters develop.
These steps can also help you feel better with oral herpes:
- Put ice in a washcloth, or a warm washcloth, on the sores to ease pain.
- Avoid hot drinks, spicy and salty foods, and citrus.
When to see a doctor
Contact your provider if a mouth ulcer does not go away after 3 weeks, if mouth ulcers return often, or if new symptoms develop. Contact your provider if oral herpes symptoms are severe or do not go away after 2 weeks. Also contact your provider if you have sores or blisters near your eyes, or if you have herpes symptoms and a weakened immune system.
Herpes infection may be severe and dangerous if it occurs in or near the eye, or if you have a weakened immune system due to certain diseases or medicines. Mouth ulcers can lead to complications. These include cellulitis of the mouth, which can come from a bacterial infection of the ulcers, and dental infections.
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 sore, review your medicines, and arrange follow-up visits. They can also refer you to a dentist or specialist when needed.
Common questions
Are mouth sores contagious?
It depends on the cause. Canker sores are not contagious. Oral herpes can spread by touching an open sore or something that has touched the virus, such as razors, towels, or dishes.
How long do mouth sores last?
It depends on the cause. In most cases, canker sores go away by themselves. Oral herpes most often goes away by itself in 1 to 2 weeks, but it may come back.
Are canker sores the same as cold sores?
No. Canker sores are not the same as cold sores, which are caused by herpes simplex.
When is a mouth sore a reason to see a doctor?
See a provider if a mouth ulcer does not go away after 3 weeks, or if mouth ulcers return often. Some types of cancer may first appear as a mouth ulcer that does not heal.
Sources
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.
