Can mouth ulcers be transmitted to others through kissing?

Common recurrent aphthous ulcers (canker sores) are not contagious through kissing. These ulcers are associated with immune dysfunction and local trauma, and no pathogenic microorganisms are involved. In contrast, oral lesions caused by herpes simplex virus (HSV) may be transmitted via close contact, including kissing. If an oral ulcer persists for more than two weeks without improvement, prompt medical evaluation—including a thorough oral examination—is recommended.

Recurrent aphthous ulcers originate from internal physiological factors—such as immune status or systemic health—and do not involve transmissible viruses or bacteria. Even with mucosal breaks, kissing will not transmit the ulcer to another person. However, exposed ulcerated areas increase susceptibility to secondary infection. Therefore, during active ulceration, it is advisable to minimize intimate contact to reduce further mucosal injury.

Oral herpes—caused by HSV—may present with ulcer-like lesions upon rupture; the virus can spread via saliva contact. During active infection, isolation measures should be implemented, antiviral therapy initiated, and topical oral medications used to alleviate burning pain. In contrast, management of common aphthous ulcers focuses primarily on local care and relies on the body’s intrinsic immune response for mucosal healing. It is essential to distinguish clearly between these two distinct oral conditions.

During ulcer episodes, opt for soft, bland foods to minimize mucosal friction and injury. Maintain rigorous oral hygiene, regulate sleep and diet, and support overall mucosal health to shorten the total healing time of oral ulcers.