You may use an over-the-counter topical antiseptic gel, such as chlorhexidine, to reduce infection, or a pain-relief gel containing lidocaine or benzocaine to ease discomfort and help the ulcer heal. Rinse your mouth with saltwater, avoid spicy or acidic foods, and maintain good oral hygiene. If the ulcer lasts more than two to three weeks, is very painful, or keeps recurring, please see a doctor or dentist for further treatment.