Iodine

What is iodine?

Iodine is a natural element that is essential for all living things. organisms. Iodine is a member of a group of non-metallic elements called halogens; other halogens include fluorine, chlorine, and bromine.

What is iodine used for?

Iodine is used topically, orally, and by injection:

• Iodine is commonly used in current antiseptics
• Oral iodine is used in the treatment of some thyroid diseases.
• Iodine is used in radiological X-ray contrast media including Connecticut scans, cholecystograms and pyelograms, either orally or by injection into the bloodstream

Iodine can also be ingested in foods like algae, shellfish, and iodized salt. Small amounts of iodine are found in vegetables and meat.

Iodine allergy

The term "iodine allergy" is commonly used, but it is actually a misnomer. Iodine is a trace element present throughout the body and is essential for the production of thyroid hormones. It is not possible to have a true allergy to elemental iodine.

"Iodine allergy" generally refers to an allergic-type reaction to iodinated X-ray contrast media, or, less frequently, to an allergic contact reaction to povidone-iodine antiseptics (Betadine ™).

Cutaneous reactions to iodinated radiological contrast media

These reactions can be classified as immediate and not immediate:

• Immediate reactions generally begin within 20 minutes after administration of the contrast media and include itching, redness, urticaria (urticaria), angioedema and anaphylaxis.
• Non-immediate reactions start more than an hour after administration and include urticaria, angioedema, maculopapular. eruption or rarely, more severe reactions like Stevens-Johnson syndrome / / toxic epidermal necrolysis

The new iodinated contrast media have improved chemical properties and the incidence of these types of reactions is now much lower.

Most of the previous reactions to contrast media are not true. hypersensitivity reactions (immunoglobulin me antibodies are not involved) The reactions are called idiosyncratic, and unlike true hypersensitivity reactions, sensitization for the agent it is not required, nor are these reactions constantly repeated in an individual.

Risk factors for reactions to contrast media

Allergic contact reactions to povidone iodine

Povidone iodine is a commonly used antibacterial agent that is a compound of iodine and povidone, along with other additives. Povidone is also used in other products such as food, medications (eg, antihistamines, diuretics, and pain relievers), hair products and toothpaste.

Allergic contact reactions to povidone-iodine preparations are rare and can be difficult to distinguish from a irritating contact reaction to povidone iodine. Both reactions can cause redness, hardening (firmness) and multiple small blisters.

Patch Tests are often used to help diagnose an allergic contact reaction. However, false positive reactions may occur in this case due to the irritating properties of povidone-iodine under occlusion. When a positive patch test reaction occurs to povidone-iodine, it is important to confirm the results with other tests, such as the repeated open-label test (ROAT).

Systemic reactions to povidone-iodine antiseptics (eg. generalized urticaria and anaphylaxis) are extremely rare and are believed to be caused by povidone, rather than iodine.

Cross reactivity between povidone-iodine antiseptics and iodine contrast media

• A history of contact allergy to povidone-iodine antiseptics does not specifically exclude the use of iodinated contrast media. However, the risk of a reaction may slightly increase, as is the case with any other contact allergy.

• Anaphylaxis to povidone-iodine is believed to be caused by povidone and cross-reactivity between these antiseptics and iodinated contrast media has not been demonstrated.

Other skin reactions to iodine

• A chemical burn-like skin reaction can occur after prolonged skin contact with povidone-iodine-saturated curtains during surgery. These reactions have the appearance of electrical burns and are believed to be due to a direct toxic effect of povidone-iodine.
• An acneform eruption due to excess iodine in the diet, for example, from seaweed in a Japanese diet

• Halogen - A rare non-allergic skin reaction caused by high levels of halogens in the body.