Mouth ulcers are sores or open lesions within the mouth, caused by various disorders. (See also mouth sores or canker sores)

Mouth ulcers are caused by many disorders. These include:

• Canker sores
• Gingivostomatitis
• Herpes simplex
• Leukoplakia
• Oral cancer
• Oral lichen planus
• Oral thrush

The skin lesion of histoplasmosis may also appear as a mouth ulcer.

Canker sores are more common in young adults than in children or older adults.

• Pain or discomfort in the mouth
• Presence of open sores in the mouth

A health care provider or dentist usually diagnoses the type of mouth ulcer, based on the appearance and location of the lesion. Blood tests or a skin biopsy of the ulcer may be needed to confirm the cause of the problem.

The goal of treatment is relief of symptoms. The cause, if known, should be treated. Gentle, thorough oral hygiene may relieve some of the symptoms. Topical (rubbed on) antihistamines, antacids, corticosteroids, or other soothing preparations may be recommended for applying on top of the ulcer. Avoid hot or spicy foods, which often increase the pain of mouth ulcers.

The outcome varies depending on the cause of the ulcer. Many mouth ulcers are benign and heal without specific treatment. Rarely, chronic mouth ulcers can develop into oral cancer.

• Cellulitis of the mouth, from secondary bacterial infection of ulcers
• Dental infections (tooth abscesses)
• Oral cancer
• Spread of contagious disorders to other people

Call for an appointment with your health care provider if your mouth ulcers persist for longer than 3 weeks. Call for an appointment with your health care provider if mouth ulcers return frequently, or if new symptoms develop.

Good oral hygiene may help in the prevention of some types of mouth ulcers. It may also help to prevent some complications from mouth ulcers. Good oral hygiene includes brushing the teeth at least twice per day, flossing at least daily, and getting regular professional dental cleaning and examination.