A: Yes, it's possible to develop food allergies as an adult. But there's not much research on why this happens. The severity of a reaction due to a food allergy varies. Some reactions are mild — a little itching and a few hives. Others are more serious, including shortness of breath, swelling and fainting.

It's impossible to predict the severity of the allergic reaction. In addition, subsequent reactions may be more severe. For this reason, don't ignore signs and symptoms such as those you describe. Shellfish are a common cause of food allergy. It would be wise to avoid all types of shellfish until you can consult with an allergist.