What can cause frequent canker sores in an 8 year old. how can they be prevented? he gets one every month or two

Prevention: Canker sore or more specifically aphthous ulcer can be prevented by avoiding a common foam detergent found in most toothpastes called sodium laurel sulfate. Switching to biotene or other toothpaste not containing this ingredient can be the cure in preventing this painful condition. During an episode, 2000 mg of lysine in divided doses per day can decrease the symptoms and time involved to heal.