Question: are aphthous mouth ulcers contagious?
Answer: Canker sores, also called aphthous ulcers, are small, painful sores that appear inside the mouth on the lips, cheeks, on the gums, and tongue. They are appropriately named, too: In Greek, aphthae (root of aphthous) means "to set on fire." Canker sores are not contagious and can't be spread through saliva.