Acute Hyper Acute Mucosal Edema - What Exposure Could Cause This?

The patient was totally fine until he came to the dental clinic to have a few teeth extracted. He suddenly, before even leaving to go home, developed acute hyper acute swelling. The number one possibility and most likely possibility is some kind of allergic reaction to an exposure. But that wouldn't make sense to suddenly happen after a specific exposure. So where I am right now, is to treat this individual for a histamine mediated angiodema.