Mouth ulcers are caused by many disorders. These include canker sores, leukoplakia, gingivostomatitis, oral cancer, oral lichen planus, oral thrush, herpes simplex, and other disorders. The skin lesion of histoplasmosis may also appear as a mouth ulcer.

Aphthous ulcer is 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. A skin biopsy of the ulcer or blood tests may be needed to confirm the disorder causing 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 antihistamines, antacids, corticosteroids, or other soothing preparations may be recommended to apply to the mouth ulcer. Avoid hot or spicy foods, which often increase the pain of mouth ulcers.

The outcome varies with the causative disorder. Many mouth ulcers are benign and resolve 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)
• Spread of contagious disorders to other people
• Oral cancer

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 recur frequently, or if new symptoms develop.

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