There are different types of mouth sores. They can occur anywhere in the mouth including bottom of the mouth, inner cheeks, gums, lips, and tongue.
Causes
Mouth sores may be caused by irritation from:
- A sharp or broken tooth or poorly fitting dentures
- Biting your cheek, tongue, or lip
- Burning your mouth from hot food or drinks
- Braces
- Chewing tobacco
Cold sores are caused by the herpes simplex virus. They are very contagious. Often, you will have tenderness, tingling, or burning before the actual sore appears. Cold sores most often begin as blisters and then crust over. The herpes virus can live in your body for years. It only appears as a mouth sore when something triggers it, such as:
- Another illness, especially if there is a fever
- Hormone changes (such as menstruation)
- Stress
- Sun exposure
Canker sores are not contagious. They may look like a pale or yellow ulcer with a red outer ring. You may have one, or a group of them. Women seem to get them more than men. The cause of canker sores is not clear. It may be due to:
- A weakness in your immune system (for example, from the cold or flu)
- Hormone changes
- Stress
- Lack of certain vitamins and minerals in the diet, including vitamin B12 or folate
Less commonly, mouth sores can be a sign of an illness, tumor, or reaction to a medicine. This can include:
- Autoimmune disorders (including systemic lupus erythematosus)
- Bleeding disorders
- Cancer of the mouth
- Infections such as hand-foot-mouth disease
- Weakened immune system -- for example, if you have AIDS or are taking medicine to suppress your immune system after a transplant
Drugs that may cause mouth sores include aspirin, beta-blockers, chemotherapy medicines, penicillamine, sulfa drugs, and phenytoin.
When to Contact a Medical Professional
Contact your health care provider if:
- The sore begins soon after you start a new medicine.
- You have large white patches on the roof of your mouth or your tongue (this may be thrush or another type of infection).
- Your mouth sore lasts longer than 2 weeks.
- You have a weakened immune system (for example, from HIV or cancer).
- You have other symptoms like fever, skin rash, drooling, or difficulty swallowing.
What to Expect at Your Office Visit
Your provider will examine you, and closely check your mouth and tongue. You will be asked questions about your medical history and symptoms.
Treatment may include:
- A medicine that numbs the area such as lidocaine to ease pain. (DO NOT use in children.)
- An antiviral medicine to treat herpes sores. (However, some experts do not think medicine makes the sores go away sooner.)
- Steroid gel that you put on the sore.
- A paste that reduces swelling or inflammation (such as Aphthasol).
- A special type of mouthwash such as chlorhexidine gluconate (such as Peridex).
Alternative Names
Aphthous stomatitis; Aphthous ulcers; Herpes simplex; Cold sores; Canker sores
References
Jordan RC. Diseases of the mouth and salivary glands. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 393.
Simon L, Silk H. Diseases of the mouth. In: Kellerman RD, Rakel DP, Heidelbaugh JJ, Lee EM, eds. Conn's Current Therapy 2023. Philadelphia, PA: Elsevier 2023:1070-1075.
Sciubba JJ. Oral mucosal lesions. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 87.
Review Date 9/10/2023
Updated by: Josef Shargorodsky, MD, MPH, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.