Are Canker Sores (Aphthous Ulcers) contagious? –
Are canker ulcerations contagious?
Do you have to worry about spreading your sores to other people?
If you suffer from aphthous ulcers (canker sores), something that may be at the top of your list of concerns is if they are contagious or not. After all, no one wants to spread their problems to others. Especially those they are closest to.
The good news is they are not.
That’s different from some other types of oral lesions.
If you mistakenly thought that they were contagious, you may be confusing your canker ulcerations with some other type of oral lesion, like cold sores (which are).
And since these two types of mouth sores are confused by so many people, we’ve created a page that provides instructions that describe how to distinguish between the two. You can find it here: Canker sores vs. Cold sores – How to tell them apart.
The biology of canker sore formation explains why they’re not contagious.
It’s easy to understand why aphthous ulcers aren’t contagious, once you know a few of the details about how and why they form.
Many disease processes are initiated by infective agents (like bacteria or viruses). And if the agent is passed from an infected person to someone else, that second person is at risk for developing the same disease process.
In cases where it’s possible for the active infective agent to be transmitted from one person to another successfully, the disease is considered contagious. The method of transmission may be direct (like touching a sore) or via infected bodily discharges or fluids (like respiratory droplets or saliva). The potential for transmission may vary as the disease process waxes or wanes.
Cold sores are an example of a contagious disease process. These lesions are caused by an infective agent (a virus) and it can be spread from one person to another.
The method of spread can be direct contact with a person’s lesion (touching, kissing, etc…) or via their body fluids (like saliva). The potential for transmission varies throughout the lifespan of a person’s lesion(s) due to the varying levels of virus particles that it sheds during different stages of formation and healing.
Aphthous ulcers (Canker sores) are not contagious.
Direct or indirect contact with a lesion will not spread it.
How canker sores differ and why they are not contagious.
Canker ulcerations are caused by an immune system response.
The formation of canker sores is the result of a specific form of immune system response to the presence of chemical compounds (molecules) referred to as antigens. (We explain the whole process here: The biology of Canker Sore formation. )
So, as opposed to a contagious disease model where a lesion might be teaming with the replicating microbes that caused it that could be transmitted, the “invaders” that initiate canker sore formation are “foreign” molecules termed “antigens” that have been detected (quite possibly just at minute levels) in oral skin tissue by the person’s own immune system.
As for the ulceration itself, it doesn’t form due to tissue destruction caused by ever growing numbers of the invasive agent (which might then be spread) but instead by the person’s own immune system response. The tissue destruction that takes place is actually “self-inflicted” in the sense that it’s caused by a person’s own white blood cells. So, with canker lesions, there’s no infective agent really to be transmitted.
We’ll also point out that many of the chemical compounds thought to act as the triggering antigen for canker sore formation (medicines, compounds in foods, toothpaste ingredients, etc…) aren’t really items that are held in the mouth or sores long enough or in quantity enough that they could be passed to others in a meaningful way.
Associated page: Known and theorized Canker sore outbreak triggers.
And that’s why canker sores are not contagious.
Generally, the characteristics associated with canker sores simply don’t lend themselves to the situation where they could be contagious. The disease process is primarily mediated by a person’s own immune system as opposed to an “invading” infective agent that then might be transmitted to others.
Page references sources:
InformedHealth.org (nih.gov) – Canker sores (mouth ulcers): Overview.
MedlinePlus.gov – Health Topics > Canker Sores.
All reference sources for topic Dental Crowns.