Dangers of Excess Iodine

Iodine is a chemical trace element commonly found in your body and is important for the synthesis of thyroid hormones. Iodine is found in small amounts in soil and seawater, and gets into the food supply in nearly everything you eat. Your thyroid gland pulls iodine from your bloodstream to use in the synthesis of thyroid hormones, which have numerous effects throughout your body. Excess iodine, however, can lead to hormonal imbalances that might lead to a wide range of side effects.

External Iodine

Iodine is a skin irritant, so contact with the skin might cause the appearance of a rash or hives. In severe cases, iodine might cause lesions or burns when in contact with your skin in large amounts. Vaporized iodine, which might be released during the manufacturing process for products that contain iodine, can irritate your eyes, mucous membranes and respiratory tract. When handling pure iodine, special precautions should be taken to protect your skin, eyes and lungs from exposure.

Iodine Sensitivity

Some individuals might be sensitive to iodine, particularly when it is found in high concentrations, as in some nutritional supplements containing iodized salts. Symptoms of iodine sensitivity are similar to an allergic reaction and include the appearance of a skin rash, swelling of your face and neck, difficulty breathing, nausea, vomiting and an irregular heartbeat. An allergic reaction to iodine can be a medical emergency, so seek medical attention immediately if you experience any of these effects.

Acute Toxicity

According to the Linus Pauling Institute, iodine acute toxicity, although rare, occurs when you ingest very high doses of iodine at once. Acute toxicity is considered iodine poisoning and might cause a burning of the mouth, throat and stomach, as well as fever, nausea, vomiting, diarrhea, a weak pulse and coma. Iodine acute toxicity generally only occurs when you ingest several grams of iodine at once, well above the recommended dietary allowance, or RDA, of 120 mcg to 150 mcg per day.

Hormonal Effects

Excess iodine might cause an increase in the production of thyroid hormones due to its stimulating effect on thyroid function. An overactive thyroid creates a condition known as hyperthyroidism, which, according to the Mayo Clinic, might result in sudden weight loss, rapid heartbeat, increased appetite, anxiety, tremors, sweating, frequent bowel movements, an enlarged thyroid gland, fatigue, muscle weakness, and insomnia. Excess thyroid hormones might also contribute to thyroid papillary cancer, a rare, but treatable form of thyroid cancer.