What is a good treatment for mouth ulcers that come up for no reason?

Watch your diet: If these are aphthous ulcers, which are very common, then check your diet. They can sometimes be triggered by cinnamon. They are not serious, but they can be very uncomfortable. This type of ulcer takes about 7-10 days to heal. There are several otc meds that can be purchased, but if it is severe see your dentist.

Listerine Mouth Rins: 1 st option is you can use the listerine mouthrinse 2x per day for 30 seconds. The purple or green listerine works great. If you rinse with this, it'll keep the ulcer from developing and actually go away. 2nd option is go see your dentist who has a laser equipment which can treat the ulcers and canker sores also when they first develop. See your dentist.