Not an Allergen (but problematic).
A naturally-occurring trace element in our bodies that is important for the production of our thyroid hormones, an iodine “allergy” is considered impossible to occur. Irritant reactions to iodine and some medical substances (like radiology contrast media) with iodine can be common, but as these do not tend to recur in the same individual consistently, or require a previous reaction in order to recur, or involve immunoglobulin E antibodies, they are not considered allergic reactions. These irritant reactions can be mild (some redness) but they can also be quite severe, with blisters and what look like chemical burns. Because reactions can vary even in the same individual, it is best to tell your doctor before a medical procedure or surgery if you have ever had a reaction to iodine or iodine-containing substances.
Allergic contact reactions can occur to povidone-iodine (found in a popular skin disinfectant) but this can be complicated to diagnose because of the commonality of irritant reactions to iodine and povidone-iodine.
Finally, note that iodine is a halogen, too. If you have shown some sensitivity to iodine or iodine-containing substances in the past, you may have halogen sensitivity and need to cut down on or lessen your exposure to bromides, fluorides, chlorides, and other halogens in general in your foods, but also in vitamins, skin products, and drinks. Check out this handy halogen-free diet, and learn more about peri-oral dermatitis here.
If you have a history of sensitive skin, don’t guess: random trial and error can cause more damage. Ask your dermatologist about a patch test.
On the prevalence of skin allergies, see Skin Allergies Are More Common Than Ever and One In Four Is Allergic to Common Skin Care And Cosmetic Ingredients.
To learn more about the VH-Rating System and hypoallergenicity, click here.
Regularly published reports on the most common allergens by the North American Contact Dermatitis Group and European Surveillance System on Contact Allergies (based on over 28,000 patch test results, combined), plus other studies. Remember, we are all individuals — just because an ingredient is not on the most common allergen lists does not mean you cannot be sensitive to it, or that it will not become an allergen. These references, being based on so many patch test results, are a good basis but it is always best to get a patch test yourself.
2. W Uter et al. The European Baseline Series in 10 European Countries, 2005/2006–Results of the European Surveillance System on Contact Allergies (ESSCA). Contact Dermatitis 61 (1), 31-38.7 2009
3. Wetter, DA et al. Results of patch testing to personal care product allergens in a standard series and a supplemental cosmetic series: An analysis of 945 patients from the Mayo Clinic Contact Dermatitis Group, 2000-2007. J Am Acad Dermatol. 2010 Nov;63(5):789-98.
4. Verallo-Rowell VM. The validated hypoallergenic cosmetics rating system: its 30-year evolution and effect on the prevalence of cosmetic reactions. Dermatitis 2011 Apr; 22(2):80-97
5. Ruby Pawankar et al. World Health Organization. White Book on Allergy 2011-2012 Executive Summary.
6. Misery L et al. Sensitive skin in the American population: prevalence, clinical data, and role of the dermatologist. Int J Dermatol. 2011 Aug;50(8):961-7.
7. Warshaw EM, Maibach HI, Taylor JS, Sasseville D, DeKoven JG, Zirwas MJ, Fransway AF, Mathias CG, Zug KA, DeLeo VA, Fowler JF Jr, Marks JG, Pratt MD, Storrs FJ, Belsito DV. North American contact dermatitis group patch test results: 2011-2012.Dermatitis. 2015 Jan-Feb;26(1):49-59.
8. Warshaw, E et al. Allergic patch test reactions associated with cosmetics: Retrospective analysis of cross-sectional data from the North American Contact Dermatitis Group, 2001-2004. J AmAcadDermatol 2009;60:23-38.
9. Foliaki S et al. Antibiotic use in infancy and symptoms of asthma, rhinoconjunctivitis, and eczema in children 6 and 7 years old: International Study of Asthma and Allergies in Childhood Phase III. J Allergy Clin Immunol. 2009 Nov;124(5):982-9.
10. Kei EF et al. Role of the gut microbiota in defining human health. Expert Rev Anti Infect Ther. 2010 Apr; 8(4): 435–454.
11. Thavagnanam S et al. A meta-analysis of the association between Caesarean section and childhood asthma. Clin Exp Allergy. 2008;38(4):629–633.
12. Marks JG, Belsito DV, DeLeo VA, et al. North American Contact Dermatitis Group patch-test results, 1998 to 2000. Am J Contact Dermat. 2003;14(2):59-62.
13. Warshaw EM, Belsito DV, Taylor JS, et al. North American Contact Dermatitis Group patch test results: 2009 to 2010. Dermatitis. 2013;24(2):50-99.
14. Lee S.K., Zhai H., Maibach H.I. Allergic contact dermatitis from iodine preparations: a conundrum. Contact Dermatitis. 2005 Apr;52(4):184-7.