Every health site explains what a canker sore is. These are about the part that is actually hard to find out: what happens to one over the next fortnight, and whether yours is doing it.
A sore sitting right on the gum is often not an ordinary canker sore. Gum is tough tissue bound down onto bone, and canker sores prefer lining that moves — so one there usually has something holding it there. Find the edge that touches it and the sore follows.
Canker sores are inside the mouth, on tissue that moves — inner lip, cheek, tongue. Cold sores are on the lip border or the skin outside it, and blister before they crust. Canker sores are not contagious and not viral; cold sores are both.
No. Canker sores are not caused by the herpes virus and are not contagious, so there is nothing to catch or pass on. The sore people confuse them with is the cold sore on the lip border, which is herpes. Only a clinician can say anything about anyone’s HSV status.
Two patterns hide behind that question. Sores that keep returning to one spot usually point at something local — a sharp tooth, a bracket, a cheek you keep catching. Sores that turn up anywhere point at whole-mouth triggers. Telling them apart takes a map and a few dates, not memory.
A canker sore runs through five stages: a day or two of tingling before anything shows, two to three days of the ulcer opening and hurting most, a few days at full width, several days filling in from the edges, then closed tissue by day 10 to 14.
Most canker sores heal in 7 to 14 days. A small one under 5mm is usually gone in about a week; a larger one can take two weeks or more. Pain peaks in the first three days and fades well before the sore closes.
You cannot tell from one look. A healing sore gets narrower, its edge softens from angry red to pale pink, and it hurts less. The only reliable test is to measure its width twice, two days apart, and compare.
Most canker sores close within 7 to 14 days. Past two weeks at the same width, or past three weeks at all, the useful move is an examination rather than another week of waiting — and two dated measurements are what make that appointment short.
Stress is the most commonly reported trigger for canker sores, and no article can tell you whether it caused yours. That is answerable only across several sores, the three days before each, and how often your ordinary days are stressful too.
Some people get canker sores at the same point in every cycle and most do not. It is one of the few trigger questions with a clean test, because cycle day is knowable for every sore — three or four cycles of dates settle what memory cannot.
Growing in the first three days is what canker sores do: they open, widen, then stop by about day four. Widening after that is the one size change worth acting on. Pain is not a size measurement — only two widths, two days apart, are.