Background. Preoperative disinfection with povidone-iodine results in a significant reduction of the risk for postoperative endophthalmitis and secondary irreversible vision loss in intraocular surgeries and intravitreal injections. Nevertheless, this important measure is often omitted if so-called "iodine allergy" is suspected. We analyze the physiological and allergological basis for the construct of "iodine allergy". Methods. This article is based on a selective literature review using the search term "allergy" in combination with "iodine", "povidone", "indocyanine green", or "seafood". Results. Iodine is a chemical element and an essential component of the human body. Scientific proof for the existence of an antibody-mediated allergic reaction (type I reaction) and in particular an immunoglobulin (Ig) E-mediated anaphylaxis against iodine is lacking. Chemical irritations and contact allergies (type IV reaction) induced by iodine-containing disinfectants are not antibody-mediated and do not cause anaphylaxis (type I reaction). The uncommon antibody-mediated allergies against iodine-containing disinfectants, fluorescent dyes, radiocontrast media, or seafood are not directed against the contained iodine itself but against other components of the respective formulation. Thus, allergic cross-reactivities between these different substance groups are not to be expected. Conclusion. So-called "iodine allergy" is a medical myth lacking a scientific basis and should not result in increased patient risks due to omitted preoperative disinfection.