Iodine plays an essential role in maintaining thyroid health. A small gland located in front of the neck, the thyroid helps regulate a number of bodily functions, including temperature control, metabolism and synthesis or certain hormones. If you have an underactive thyroid, iodine may be part of your medication regimen. Too much iodine, however, can have harmful side effects.
An overdose of iodine can cause abdominal pain, fever, diarrhea, vomiting, thirst or a metallic taste in your mouth. Other potential symptoms include delirium, seizures, shock or stupor. Mouth or throat pain can also occur and you may not produce any urine.
Iodine overdose can lead to hyperthroidism, or overactive thyroid. Symptoms of overactive thyroid include weight loss, increased appetite, increased sweating, heat intolerance, nervousness, tremors, fatigue or difficulty concentrating. Hyperthyroidism may also cause rapid, pounding heartbeat, difficulty sleeping or high blood pressure. Hyperthyroidism can lead to a sudden worsening of symptoms called thyrotoxicosis, a potentially life-threatening condition that causes fever, abdominal pain and heart problems. Your eyes may bulge, a condition called exophthalmos. If these symptoms occur, seek immediate medical attention, MedlinePlus advises.
In some cases, overdoses of iodine can cause underactive thyroid, or hypothyroidism. Symptoms of hypothyroidism include fatigue, cold sensitivity, weight gain, dry skin and hair, high cholesterol levels, constipation, brittle nails, muscle aches, facial puffiness and depression.
THYROID PAPILLARY CANCER
High doses of iodine can increase your risk of developing thyroid papillary cancer, the most common type of thyroid cancer, accounting for 80 percent of cases, according to MyBiopsy, the website for the College of American Pathologists. Women develop this cancer three times more frequently than men; this cancer usually develops between the ages of 30 and 50. Radioactive iodine from nuclear fallout can cause high iodine exposure. If you have iodine deficiency, your thyroid will take up more iodine than usual, increasing your risk of developing thyroid cancer.