When do most canker sore outbreaks occur?
There seems to be a slight seasonal tendency for canker sore outbreaks.
It seems, at least to a small degree, that people suffer with canker sores more so during the summer months than at other times of the year (in the USA).
Our findings come from our "canker sores" graph.
Take a look at the chart below. It's based on 5 years of data and it seems to suggest that web search volume for the term "canker sores" rises into and subsequently tops out during the summer months (August into September). Thereafter search activity tends to wane, reaching a low point in December into January.
Similar analysis involving the term "mouth ulcers" seems to show a similar seasonal bias (see this page's second graph). Canker sores are the most common type of mouth ulcer. And for those who initially don't know what type of sore they are experiencing, "mouth ulcers" is likely a synonymous term.
Our comments about our 'canker sores' graph.
We aren't suggesting that our observation about the apparent seasonality of canker sore outbreaks should be considered a hard fact. It should instead be considered just a curiosity.
You might note that the effect we've charted is fairly minor. From the January low to the September high, the increase in search volume for keywords "canker sores" is only about 15%. With our "mouth ulcers" graph the increase in web search traffic, from lowest to highest point, is on the order of no more than 20%.
In regards to an explanation, there are a number of factors that have been suggested as being triggers for canker sore outbreaks. Of these, one might postulate that canker sores triggered by food allergies (such as those to fresh fruits and vegetables) might explain the minor seasonal effect demonstrated above.
About the data we evaluated.
In regards to the data we have used to create our graph, we evaluated yearly Google search data (2004 - 2009) for the keywords "canker sores" and "mouth ulcers." For each calendar year, the month that had the greatest search volume was set to a value of 100. We then calculated the relative value for the lesser months. After combining the five years of data (with all years receiving equal weighting), we again normalized the month with the highest cumulative search volume to 100 and then calculated the relative value for each of the lesser months.