No, it has nothing to do with werewolves or Harry Potter. Lupin (also sometimes called lupine) is a bean, and the FDA recently warned that it can cause a variety of allergic reactions. These could be as mild as hives, swelling, and itchiness — or as severe as a deadly bout of anaphylaxis. Although lupin beans are popular in Europe (pickled, on their own, or as an additive), they're a relatively new ingredient to the US. So, the FDA just wants to make sure we're all caught up on our lupinfo.
The bean is a common ingredient in many gluten-free products because it can be used to make flour and can be added to other flours for texture or taste. Products containing lupin include pastas, breads, and cereals — pretty much anything that comes in a gluten-free variety. And, studies show that people with existing legume allergies (especially those allergic to peanuts) are at a greater risk for developing an allergy to lupin as well.
So, be on the lookout for this newcomer to the gluten-free game. And, if peanuts are already a problem for you, steer clear. Nothing ruins a tasty meal like anaphylactic shock.