Treatment is usually not necessary. In most cases, the canker sores go away by themselves.

Severe mouth ulcers (larger than 1 cm or lasting longer than 2 weeks) may require evaluation and treatment. In these cases, topical or oral (by mouth) tetracycline suspension may be given, with instructions to hold it in the mouth for 2-5 minutes before swallowing.

Tetracycline is usually not prescribed for children until after all the permanent teeth have fully developed. If children use tetracycline suspension before their permanent teeth are fully developed, it can permanently discolor teeth that are still forming. Multiple, painful mouth ulcers may treated with an antiviral agent such as acyclovir.

Topical or oral corticosteroids are rarely used, but they may reduce inflammation. Dexamethasone suspension may be given with instructions to rinse the mouth and spit it out; or dexamethasone, prednisone, or other corticosteroid may be given systemically (in a pill or injection, for example).

Avoid hot or spicy foods to minimize discomfort. Mild mouth washes such as salt water or over-the-counter mouth washes may help. Over-the-counter topical medications (applied to a specific area of the mouth) may reduce discomfort and soothe the ulcerated area.

To prevent bacterial infection, brush and floss your teeth regularly and visit the dentist for routine care.

The easiest home remedy is to apply hydrogen peroxide (1 part hydrogen peroxide and one part water with a cotton swab) to the canker sore. Then dab a small amount of milk of magnesia on the canker 3-4 times a day. This is not only soothing, but appears to help healing.

Canker sores usually heal spontaneously. The pain usually decreases in 3 or 4 days. Other symptoms disappear in 10 to 14 days.

• Oral thrush or other Candida infections may occur following the use of antibiotic treatment for cankers
• Rarely, secondary bacterial infections may occur (cellulitis, Ludwig's angina)
• Oral cancer is not a complication of canker sores, but if an ulcer lasts more that 2 weeks, cancer may actually be the cause of the ulcer. Therefore, any ulcer lasting over 2 weeks should be evaluated by a physician.

Apply home treatment and call your health care provider if symptoms of canker sores persist or worsen, or canker sores recur more often than 2 or 3 times per year.

Call your health care provider if symptoms are associated with other problems such as fever, diarrhea, headache, or skin rash.