Severe food allergies can make it tricky to buy foods with processed ingredients, which is why the FDA requires labeling of foods that contain commonly allergenic foods like nuts. But more and more manufacturers are including "accidental-allergy" warnings on foods that formerly didn't carry labels. These accidental warnings may be tacked on when a food is processed in a plant that also processes other, more allergenic foods. But because there are no guidelines for this kind of labeling, consumers are getting confused, and often not heeding the warnings.

A recent survey found that when consumers read that a product may contain an allergenic ingredient, they avoided it about 88% of the time. But when the label contained an accidental-allergy warning, consumers were more likely to ignore the warning. Though the risk is small, a recent study found that about 7% of foods (and possibly more) contained traces of the foods they were warning against, just because they were processed in the same plant.

The FDA is asking for consumer input and may intervene before the end of the year. Until then, say allergy experts, if your allergy is severe, heed the warning, even if you've eaten the food before.