Are mouth ulcers contagious?

The most common type, aphthous stomatitis, is not contagious. However, herpetic (viral) stomatitis, which produces blisters, can spread through saliva or direct contact, so while you have symptoms keep your towel, utensils, and cups separate and avoid kissing. If the blisters spread or you develop a fever, antiviral treatment may be needed, so please come in.