Iodine is a mineral used topically for antibacterial purposes or intravenously as a component of radiological contrast agents. Iodine is necessary to support healthy thyroid functioning. Some people, however, are highly sensitive to this mineral and exhibit symptoms of an iodine allergy that will progress with each additional exposure. According to the University of California, San Francisco, these symptoms will exhibit within two hours of exposure.
Symptoms of an iodine allergy commonly present on the skin. With or without a visible rash, an itching sensation, or pruritis, may develop immediately after iodine exposure or injection. Red, raised rashes can develop anywhere on the body and can progress quickly to a generalized reaction of hives, or painful red welts usually on the torso.
Face and Lips
An early ominous sign of iodine allergy is the tingling of the lips, possibly progressing to the entire face, according to Cleveland Clinic. Angioedema refers to a generalized swelling underneath the skin and is prominent around the eyes, tongue and lips. Due to the potential for tracheal constriction, angioedema can quickly lead to a life-threatening situation.
Rhinitis, or a runny nose, may signal an impending allergic reaction. Indicative of a serious allergy to intravenous exposure of iodine, rhinitis may precede development of a wheeze, or a whining sound with each breath. This wheezing sound is created by the spasms of the bronchioles, or main breathing tubes, due to a massive histamine release from the allergy response.
Vomiting and diarrhea can be seen with an iodine allergy. Vomiting, diarrhea and stomach cramping is more common with ingested iodine such as that found in shellfish. Diarrhea will not be an immediate side effect, rather experienced hours after the exposure to iodine.
A life-threatening situation, anaphylactic reactions to iodine will present with highly specific symptoms immediately after exposure, or recurrent exposure in someone known to have sensitivity to iodine. Symptoms of this degree of allergic response may include wheezing, shortness of breath, swelling of the face and lips, decreasing blood pressure and increasing heart rate, according to MedlinePlus. If untreated, anaphylactic reactions will lead to death.