Clinical variants of recurrent aphthous stomatitis (RAS)19
| Minor | Major | Herpetiform | |
| Number | Single to few ulcers | Single to few ulcers | Multiple ulcers 10+ |
| Location | Most common on labial and buccal mucosa and floor of the mouth | Often present on lips, soft palate and fauces | Often present on labial and buccal mucosa and floor of the mouth |
| Size | <1 cm diameter | Deep and >1 cm | Small, >5 mm but multiple ulcers may group to form a larger lesion |
| Duration | Heal within 10–14 days | Persist for up to 6 weeks | Last for about 10–14 days |
| Healing | No scarring | Possible scarring | Possible scarring particularly when grouped ulceration occurs |