If you have an iodine allergy, you may not realize it unless you have iodine administered topically or intravenously during medical treatment. Iodine allergy can result in severe allergic symptoms, including life-threatening anaphylactic shock. Many people share common misconceptions about this condition, so it is important to know exactly what an iodine allergy is and how it manifests.
Iodine is a non-metallic element that plays an important role in the human body. It triggers the release of thyroid hormones, which control a number of important metabolic processes. People with iodine deficiencies may develop a goiter, hypothyroidism or mental symptoms. Because many diets do not include sufficient amounts of iodine, salt manufacturers iodize table salt, which supplies the necessary amount of this element and helps prevent symptoms of low iodine. Iodine is also used topically as a wound disinfectant, and intravenously as a contrast dye for imaging studies such as an intravenous pyelogram (IVP) or an angiogram. Iodine is also present in surgical preparation scrubs, such as Betadine.
Iodine allergies do not occur from consumption of foods containing iodine. While shellfish allergies are not usually caused by the iodine, there is some evidence that people with such allergies may have a slightly higher risk of iodine allergy. Instead, iodine allergy occurs as a reaction to either topical or intravenous administration of iodine. A Washington University study suggests about 15 percent of patients have adverse reactions to iodine contrast mediums; however, not all of those reactions are true allergic reactions as measured by an IgE antibody response. Another study at the University of Michigan suggests that only about 0.6 percent of patients have allergic-like symptoms such as hives, soft tissue swelling, and anaphylaxis.
Symptoms range from mild to immediately life threatening, and include:
- Itching, rash, or hives
- Watery eyes or runny nose
- Throat, tongue and lip tingling or swelling, ranging from mild up to anaphylactic shock
- Swelling of internal or external tissues
If you topically administer iodine as a wound disinfectant and experience any of the above symptoms, seek medical care. In the case of anaphylactic symptoms, seek emergency treatment. If you experience a reaction to topical or intravenous iodine, a health care professional will administer an epinephrine injection in order to stop your body's histamine reaction. Other treatments include corticosteroids, albuterol, nitroglycerine and diphenhydramine.
If you are having a radiographic study utilizing iodine as a contrast element, tell the doctor if you have ever had any reaction to iodine before, including mild reactions. You should also report a shellfish allergy. Radiologists can use alternatives to iodine contrast dyes in patients with iodine sensitivity.
According to MayoClinic.com, reaction to radiocontrast dye is not related to shellfish allergy. Iodine occurs naturally in many foods, and there is little evidence that it causes allergic reactions when ingested. Allergies to foods high in iodine such as seafood and shellfish most likely result from something else in the foods themselves. Such food allergies can be quite severe, so if you experience any numbness, swelling or tingling in the lips, mouth or throat, seek immediate medical evaluation. Eating foods containing iodine is essential for thyroid health, so do not avoid them unless your doctor specifically tells you that you should.
While iodine allergy can be severe, the condition is relatively rare. If you've ever experienced a reaction to topical iodine or an iodine radio contrast medium, talk with your doctor.