iodine (generic name)
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SafetyDISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.
Some individuals are allergic/hypersensitive to iodide or to organic preparations containing iodine. Hypersensitivity reactions may involve rash, angioedema (throat swelling), cutaneous/mucosal hemorrhage (bleeding), fever, arthralgias (joint pains), eosinophilia (abnormal blood counts), urticaria (hives), thrombotic thrombocytopenic purpura, or severe periarteritis (inflammation around blood vessels). Reactions can be severe and deaths have occurred with exposure.
Topical use of iodine preparations may irritate/burn tissues and cause sensitization in some individuals.
This review does not comprehensively cover the use of iodine-based intravenous contrast media for CT scan imaging, although serious life-threatening allergic reactions have been associated with use. Individuals with known or suspected iodine hypersensitivity should inform their physician prior to receiving contrast media.
Side Effects and Warnings
Note: This review does not cover adverse effects associated with intravenous iodine-based contrast agents used for CT scan imaging or radioactive iodine.
Iodine preparations used orally (by mouth) or topically (on the skin) are generally considered to be safe in healthy non-allergic individuals when used in recommended amounts, not exceeding tolerated upper limits. Higher amounts taken acutely or chronically may result in adverse effects.
Acute iodine poisoning is rare and generally occurs only with doses of many grams. Symptoms may include burning of the mouth, throat, and stomach, fever, nausea, vomiting, diarrhea, cardiovascular compromise, and loss of consciousness/coma.
Chronic iodism, also known as iodide intoxication, may cause eye irritation, eyelid swelling, unpleasant/metallic taste, burning or swelling of the mouth/throat, soreness of the gums/teeth, increased salivation, gastrointestinal upset, diarrhea, anorexia, flu-like symptoms, sneezing, cough, pulmonary edema (fluid in the lungs), confusion, headache, fatigue, depression, numbness, tingling, pain, weakness, muscle aches, easy bruising, irregular heart beat, or acne-like skin lesions. Prolonged excess intake of iodide can lead to thyroid gland dysfunction including hypo- or hyperthyroidism, parotiditis, thyroid gland hyperplasia (enlargement), thyroid adenoma, goiter, autoimmunity, and elevated thyroid stimulating hormone (TSH) levels.
Individuals with autoimmune thyroid disease (AITD) may have increased sensitivity to adverse effects of iodine. Those with previous iodine deficiency or nodular goiter may be particularly susceptible. Patients should be aware that kelp supplements also contain iodine, as a kelp-containing tea has been reported to cause iodine-induced hypothyroidism.
Topical cadexomer iodine has been associated with local burning sensation in clinical trials. Cutaneous (skin) intolerance may develop with the topical use of iodinated polyvidone. Other reported reactions to tinctures include rash, blistering, crusting, irritation, itching, or erythema (reddening) of skin. Topical use of iodine may stain the skin.
Sodium iodide should be used cautiously in those with gastrointestinal obstruction.
Povidone-iodine bladder irrigation has been associated with increased risk of urinary tract infection.
Internal administration of povidone may cause serious side effects that may even lead to kidney failure or death.
Pregnancy and Breastfeeding
Iodine requirements are increased during pregnancy. Iodine supplementation during pregnancy may be particularly relevant in areas of endemic iodine deficiency, such as non-industrialized nations. Iodine deficiency during pregnancy has been associated with an increased incidence of miscarriage, stillbirth, birth defects, and mental retardation. Moreover, severe iodine deficiency during pregnancy may result in congenital hypothyroidism in the newborn. In contrast, excess iodine intake by pregnant women may lead to effects of excess iodine in the fetus/newborn, including thyroid dysfunction or skin irritation.
It has been suggested to avoid topical use of povidone-iodine for perianal preparation during delivery or postpartum antisepsis due to possible iodine absorption by the newborn or absorption by the mother leading to increased breastmilk iodine concentrations. Other reports suggest that this may not be a significant concern.
Iodine supplementation during breastfeeding may be particularly relevant in areas of endemic iodine deficiency, such as non-industrialized nations. Infants are particularly vulnerable to the effects of iodine deficiency and iodine deficient women may not be able to provide sufficient iodine in their breastmilk.