hmmmm… I actually don’t know myself about the seriousness of the hives, but if I were you, I would give it try. I would want to find out what was causing the problem for sure, so as to avoid it in the future. That makes more sense to me than just hoping that they won’t come back, you know?
If you are really worried, watch him carefully and make sure you have some benedryl on hand in case they seem to get really bad or he seems to have trouble breathing, etc.