IODINE: Overview, Uses, Side Effects, Precautions, Interactions ...

Overview
Iodine is an element that is used by the thyroid. Humans cannot produce iodine, so it must be consumed. It is added to some foods and also to salt.
Iodine reduces thyroid hormone and can kill fungus, bacteria, and other microorganisms such as amoebas. Iodine deficiency is one of the most common and preventable world health problems. Most iodine is found in the ocean, where it is concentrated by sea life, particularly in seaweed.
Iodine is taken by mouth to prevent and treat iodine deficiency and its consequences, including goiter and some thyroid disorders. A specific kind of iodine called potassium iodide is also US FDA approved to prevent thyroid damage after a radioactive accident. Iodine is also used for pink eye, gum infections, wound healing, and many other conditions, but there is limited scientific evidence to support many of these uses.
Uses & Effectiveness ?
Likely Effective for
Radiation exposure. Taking iodine by mouth can protect the thyroid after exposure in a radiation emergency. But it should not be used for general protection against radiation.
Possibly Effective for
Pink eye. Using eye drops containing iodine in the form of povidone-iodine seems to reduce the risk of pink eye in newborns. It also seems to help treat pink eye in adults.
Foot sores in people with diabetes. Applying iodine to foot sores might help treat foot ulcers related to diabetes.
Swelling (inflammation) of the lining of the uterus (endometritis). Washing the vagina with a solution containing iodine in the form of povidone-iodine before a cesarean delivery reduces the risk of swelling of the uterus lining.
Swelling (inflammation) and sores inside the mouth (oral mucositis). Rinsing the mouth with an iodine solution seems to prevent soreness and swelling inside the mouth caused by chemotherapy.
A serious gum infection (periodontitis). Rinsing the mouth with an iodine solution during non-surgical treatments for gum infections can help reduce the depth of infected gum pockets.
Infection after surgery. Applying iodine in the form of povidone-iodine before or during surgery reduces the risk of infections. But it's unclear how it compares to other options, such as chlorhexidine, for preventing infections.
A life-threatening condition caused by excess of thyroid hormone (thyroid storm). Taking iodine by mouth in combination with other treatments can help treat thyroid storm.
Lumps in the thyroid. Taking iodine by mouth can improve lumps on the thyroid called thyroid nodules.
Possibly Ineffective for
Infections in people with catheters. Applying povidone-iodine where a dialysis catheter is inserted doesn't seem to work as well as chlorhexidine for reducing the risk of a blood infection. Applying povidone-iodine before inserting a urinary catheter doesn't reduce the risk for infection.
Growth and development in premature infants. Feeding premature infants iodine supplements doesn't improve their brain development nor reduce their risk of dying.
There is interest in using iodine for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.
Side Effects
When taken by mouth: Iodine is likely safe for most people when taken in doses less than 1100 mcg daily. Large amounts or long-term use of iodine is possibly unsafe. Adults should avoid prolonged use of higher doses without proper medical supervision. Higher intake can increase the risk of side effects such as thyroid problems. Iodine in larger amounts can cause metallic taste, soreness of teeth and gums, burning in mouth and throat, stomach upset, and many other side effects.
When applied to the skin: Iodine is likely safe for most people when appropriately diluted products are used. A 2% iodine solution is an FDA-approved prescription product.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Iodine is likely safe when taken by mouth in recommended amounts or when applied to the skin appropriately using an approved product (2% solution). Do not take more than 1100 mcg of iodine daily if you are over 18 years old; do not take more than 900 mcg of iodine daily if you are 14-18 years old. Iodine is possibly unsafe when taken by mouth in high doses. Higher intake might cause thyroid problems in the baby.
Children: Iodine is likely safe when taken by mouth in appropriate doses depending on age. Doses should not exceed 200 mcg daily for children 1 to 3 years old, 300 mcg daily for children 4 to 8 years old, 600 mcg daily for children 9 to 13 years old, and 900 mcg per day for adolescents.
Thyroid disorders: Prolonged use or high doses of iodine might make certain thyroid disorders worse, including hypothyroidism, an enlarged thyroid gland (goiter), or a thyroid tumor. Also, people with autoimmune thyroid disease might be especially sensitive to the harmful effects of iodine.
Special Precautions and Warnings
When taken by mouth: Iodine is likely safe for most people when taken in doses less than 1100 mcg daily. Large amounts or long-term use of iodine is possibly unsafe. Adults should avoid prolonged use of higher doses without proper medical supervision. Higher intake can increase the risk of side effects such as thyroid problems. Iodine in larger amounts can cause metallic taste, soreness of teeth and gums, burning in mouth and throat, stomach upset, and many other side effects.
When applied to the skin: Iodine is likely safe for most people when appropriately diluted products are used. A 2% iodine solution is an FDA-approved prescription product.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Iodine is likely safe when taken by mouth in recommended amounts or when applied to the skin appropriately using an approved product (2% solution). Do not take more than 1100 mcg of iodine daily if you are over 18 years old; do not take more than 900 mcg of iodine daily if you are 14-18 years old. Iodine is possibly unsafe when taken by mouth in high doses. Higher intake might cause thyroid problems in the baby.
Children: Iodine is likely safe when taken by mouth in appropriate doses depending on age. Doses should not exceed 200 mcg daily for children 1 to 3 years old, 300 mcg daily for children 4 to 8 years old, 600 mcg daily for children 9 to 13 years old, and 900 mcg per day for adolescents.
Thyroid disorders: Prolonged use or high doses of iodine might make certain thyroid disorders worse, including hypothyroidism, an enlarged thyroid gland (goiter), or a thyroid tumor. Also, people with autoimmune thyroid disease might be especially sensitive to the harmful effects of iodine.
Interactions ?
Moderate Interaction
Be cautious with this combination
Amiodarone (Cordarone) interacts with IODINE
Amiodarone contains iodine. Taking iodine supplements along with amiodarone might increase the levels of iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid.
Lithium interacts with IODINE
Large amounts of iodine can decrease thyroid function. Lithium can also decrease thyroid function. Taking iodine along with lithium might decrease thyroid function too much. Do not take large amounts of iodine if you are taking lithium.
Medications for an overactive thyroid (Antithyroid drugs) interacts with IODINE
Iodine can increase or decrease thyroid function. Taking iodine along with medications for an overactive thyroid might change the effects of these medications. Do not take iodine supplements if you are taking medications for an overactive thyroid, unless recommended by a healthcare provider.
Dosing
Iodine is an essential nutrient found in iodized salt, marine products such as seaweed, as well as eggs and cow's milk. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). For adults, the RDA is 150 mcg daily. While pregnant, the RDA is 220 mcg daily. While breast-feeding, the RDA is 290 mcg daily. In children, the RDA depends on age.
Iodine is also available in supplements and in various topical solutions, eye drops, mouthwashes, ointments, and scrubs. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.
Fu, L. X., Zeng, Q. Z., Deng, l. Q., and Chen, Q. F. The effect of prevention of iodised salt on intelligency and physical development in endimic critinism of Changping of Guangdong. Symposium of the Third Chinese Endemic Goiter and Cretinism (Chinese) 1987;(153):155.
Kokavec, M. and Fristakova, M. [Efficacy of antiseptics in the prevention of post-operative infections of the proximal femur, hip and pelvis regions in orthopedic pediatric patients. Analysis of the first results]. Acta Chir Orthop.Traumatol.Cech. 2008;75(2):106-109. View abstract.
Shrestha, R. M. Effect of iodine and iron supplementation on physical, psychomotor and mental development in primary school children in Malawi [doctoral thesis]. Wageningen, The Netherlands: Wageningen Agricultural University. 1994;
Shu, Y. Q. [Analysis of children intelligence in IDD areas after correction of iodine deficiency]. Symposium of the Third Chinese Endemic Goiter and Cretinism (Chinese) 1987;197-198.
Tajtakova, M., Langer, P., Hancinova, D., and Gonsorcikova, V. Thyroid volume and function in 13-year-old children after 2 years of supplementation with small doses of iodine. Cesko Slovenska Pediatrie 1994;49(6):340-343.
Li F, Wan S, Zhang L, et al. A Meta-Analysis of the Effect of Iodine Excess on the Intellectual Development of Children in Areas with High Iodine Levels in their Drinking Water. Biol Trace Elem Res 2022;200(4):1580-1590. View abstract.
CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.