<<Disclaimer: Verify this information before applying it to your situation.>> Her is the overdue summary on reaction time. After reading the following in a previous post, which was answering a question about how to determine if one was celiac, I wanted to know if this was typical, because it is not the case with me. One specific tip off is the time of onset of an episode. After ingesting gluten, the gut reaction is usually within 30 minutes of a meal. The responses indicate that reaction time varies from just a few minutes to several days and that it can change over time. The following groupings are approximate. A few minutes to about a half hour - 15 About 2-12 hours - 11 12-24 hours - 14 2 to 48 hours - 1 48 hours - 4 3 days - 1 no reaction to accidents - 1 (This person took 6 days to react with a challenge.)