How is canker sore treated?

Canker sore. OTC treatments can help. Avoid spicy and acidic foods and drinks. Your dentist can help.
Aphthous ulcers. Treatment depends on cause. Aphthous stomatitis involving the common canker sore can occur in up to 15% of americans, and may involve some bacteria like staph epidermidis. However, similar-appearing aphthous ulcers can be seen with herpes, crohn's disease, and other systemic disorders, if you have multiple aphthous ulcers or frequently recurring ones please have the lesions checked out.
Licorice. Licorice has been used since ancient times for canker sores (also known as apthous ulcers) in the mouth. Also, small studies show it can be effective when used as a mouthwash -- 50-75% improvement in 1 day. sucking on dgl lozenges may work also. Other studies showed positive results with a dissolving licorice disk placed on the sore.
Canker Sores. Pain from a canker sore generally lessens in a few days and the sores usually heal without treatment in about a week or two. If sores are large, painful, or persistent, your dentist may prescribe an antimicrobial mouth rinse, a corticosteroid ointment, or a prescription or nonprescription solution to reduce the pain and irritation.