How can canker sores or mouth ulcers be caused by stress?

Thru immune system: The exact interaction between stress and the cause of canker sores is not well known, but stress causes a reaction in the immune system. There is a series of hormones and mediators released when there is stress. The immune system is weaker. Exactly how this causes canker sores is not understood but this relationship is accepted.

Decrease immunity: Cankors are frequently caused by viruses (usually herpetic in nature). Humans respond to stress in many, many ways. Even though nobody knows the exact methodology, stress has been known to have a negative effect on the immune system. Specifically, there can be a suppression in the immune system that allow viruses to be expressed. That is the general consensus. Hope that helps!

May contribute to: The cause of canker sores, also known as aphthous ulcers, is not well understood. Local irritation, stress and a possible autoimmune component are the most common theories. It is not caused by a virus, as many believe and is often confused or lumped in with herpetic cold sores that are caused by a virus. More information at: http://neurosurgery.Med.Nyu.Edu/content?Chunkiid=11983.

Immune system: Stress can greatly affect the immune system and in fact induces the production of many so-called neurokinins and substance p, which affect your immune function. As pointed out by others , the cause is unknown. My suspicion, not proven scientifically, is that it is related to the same bacterium called strep mutans which is linked to dental cavities since topical antibiotics often hasten recovery.

Stress & mouth sores: The reason stress can cause mouth sores is that stress can cause a decrease in your immune system. This in turn can cause different types of problems like apthous ulcers, or stress ulcers to arise in your mouth. Other lesions like herpes simplex, or canker sores on the lips also will arise because the virus causing the lesion is left unchecked by the decrease in the immune system.