Minor aphthous ulcers present, small round or ovoid ulcers of 2 to 4 mm in diameter, occur in groups of up to 6 at a time, and are found mainly on the non-keratinised mucosa of the lips, cheeks, floor of the mouth, sulci, or ventrum of the tongue. They heal in 7 to 10 days, and recur at intervals of 1 to 4 months, generally leaving little or no evidence of scarring.