What is an iodine allergy?
An iodine allergy is a relatively rare allergic reaction that occurs when large amounts of iodine come into contact with the body. Iodine is also a vital substance that the body needs in order to produce thyroid hormones, for example. People with an iodine allergy generally do not react to the iodine in food, so that they can absorb sufficient iodine through food despite the allergy. The allergic reaction is more likely to occur if, for example, a disinfectant containing iodine is used, or after contact with X-ray contrast media or after taking iodine-containing medication.
What causes the iodine allergy?
If iodine is supplied to the body, it is absorbed by the body through a mucous membrane. The immune system checks whether the substance is dangerous or harmless. Sometimes this differentiation is not reliable and iodine is mistakenly perceived as a dangerous substance.
This is called sensitization. Only when symptoms occur is it called an allergy. Allergy to iodine belongs to the group of late type allergies (type 4).
At the first contact with iodine, it is absorbed and specific cells (T-lymphocytes) are formed in the lymph nodes, which react sensitively to iodine (sensitization phase). The trigger or effector phase only begins with the next contact with iodine. The T-lymphocytes recognize the iodine and trigger a cascade of immune reactions. In connection with this immune reaction, messenger substances are released, which in turn promotes inflammation in the tissue and thus leads to the known symptoms of an allergic reaction.
How can an iodine allergy be determined?
The diagnosis is usually made by an allergologist. Through a detailed conversation, it can be discussed in which situations the allergic reaction occurs. This allows the triggering substances to be identified.
In the case of iodine allergy, this can sometimes be difficult, since most patients do not react to the iodine in food, but only show a reaction when large quantities of iodine are ingested, for example during a contrast medium examination. In an analysis of the blood, substances can be identified which are found increased in the case of an allergy. The next step would be a provocation test by applying some iodine to a skin area and waiting for the reaction to occur.
