How do you know if you have a gastrografin allergy?

Iodine allergy: Here is the fda blurb: anaphylactic reactions: anaphylactic reactions, including fatalities, have been reported with the use of gastrografin. Patients at increased risk include those with a history of a previous reaction to a contrast medium, patients with a known sensitivity to iodine, and patients with a known clinical hypersensitivity (bronchial asthma, hay fever, and food allergies). Medical p.