Could zilactin b irritate canker sores?

It's possible. Although zilactin is intended to manage the symptoms of canker sores and other oral soft tissue irritation, some patients will occasionally develop a sensitivity reaction to one of its components. In these cases, use of this product would be counter-productive, and it should be discontinued if irritation occurs.
Yes. Zilactin treats canker sores by chemically cauterizing (mildly chemically burning) the nerve endings and the proteins on the surface. Some people feel that the area is irritated, rather than relieving the pain.