Iodine - What is it & How to use

Iodine reduces thyroid hormone and can kill fungus, bacteria, and other microorganisms such as amoebas. A specific kind of iodine called potassium iodide is also used to prevent thyroid damage after a radioactive accident.

Effectiveness

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for IODINE are as follows:

Likely effective for…

  • Iodine deficiency. Taking iodine supplements, including iodized salt, is effective for preventing and treating iodine deficiencies.
  • Radiation exposure. Taking iodine by mouth is effective for protecting against exposure to radioactive iodides in a radiation emergency. However, it should not be used for general protection against radiation.
  • Thyroid conditions. Taking iodine by mouth can improve thyroid storm and lumps on the thyroid called thyroid nodules.
  • Leg ulcers. Applying iodine in the form of cadexomer iodine or povidone-iodine to venous leg ulcers along with compression therapy seems help heal leg ulcers and reduce the chance of a future infection.

Possibly effective for…

  • Conjunctivitis (pinkeye). Research suggests that using eye drops containing iodine in the form of povidone-iodine is more effective than silver nitrate for decreasing the risk of pinkeye in newborns. However, it is not more effective than the medications erythromycin or chloramphenicol.
  • Foot ulcers in diabetes. Applying iodine to foot ulcers might be beneficial for people with foot ulcers related to diabetes.
  • Inflammation 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 the inflammation of the uterus.
  • Painful fibrous breast tissue (fibrocystic breast disease). Research shows that taking iodine, especially molecular iodine, reduces painful fibrous breast tissue.
  • Breast pain (mastalgia). Taking 3000-6000 mg of molecular iodine for 5 months seems to reduce pain and tenderness in women with breast pain related to their menstrual cycle. However, taking lower doses of 1500 mg daily doesn’t seem to work.
  • Soreness and swelling inside the mouth. Applying iodine to the skin seems to prevent soreness and swelling inside the mouth caused by chemotherapy.
  • Gum infection (periodontitis). Research suggests that rinsing with a solution containing iodine in the form of povidone-iodine during non-surgical treatments for gum infections can help reduce the depth of infected gum pockets.
  • Surgery. Some research suggests that applying iodine in the form of povidone-iodine before or during surgery reduces the risk of infections. However, conflicting results exist. Also, povidone-iodine seems to be less effective than chlorhexidine at preventing infections at the surgical site when used before surgery.

Possibly ineffective for…

  • Catheter-related infection. Some evidence suggests that applying povidone-iodine reduces the risk of blood stream infections for people with hemodialysis catheters. However, most research suggests that applying povidone-iodine where a catheter is inserted does not reduce the risk of infection associated with using other types of catheters.

Insufficient evidence to rate effectiveness for…

  • Bleeding.Early research suggests that washing the tooth socket with a rinse containing iodine in the form of povidone-iodine stops bleeding in more patients after having a tooth pulled compared to saline.
  • Chyle in the urine (chyluria). Chyluria is a condition in which chyle is present in the urine stream. This causes the urine to appear milky white. Early research suggests that injecting iodine in the form of povidine-iodine into a particular region of the pelvis helps treat and prevent the recurrence of chyluria.
  • Eye infection (corneal ulceration). Early research suggests that using eye drops containing iodine in the form of povidone-iodine along with antibiotic therapy does not improve vision in people with corneal ulcers better than using antibiotics alone.
  • Fungal skin condition (Cutaneous sporotrichosis). Saturated solution of potassium iodide is commonly used for cutaneous sporotrichosis. There are reports that taking potassium iodide by mouth alone or with another antifungal treatment is effective for most people with cutaneous sporotrichosis.
  • Pneumonia. Early research suggests that rinsing the throat with iodine in the form of povidone-iodine decreases the risk of pneumonia in people with severe head trauma who are using a ventilator.
  • Wound healing. There is some interest in using iodine agents to promote wound healing. While there is some evidence that applying iodine to wounds is more effective than non-antiseptic dressings in reducing wound size, iodine seems to be less effective than antibiotics.
  • Other conditions.

More evidence is needed to rate the effectiveness of iodine for these uses.

Dose

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:

  • For iodine deficiency: Consumption of iodized salt is recommended in most cases.
    • For most people, iodized salt containing 20-40 mg of iodine per kilogram of salt is recommended. If salt consumption is less than 10 grams per person per day, the amount of iodine in salt may need to be higher.
    • In pregnant and lactating women, iodine supplements providing 250 mcg of iodine daily or a single annual dose of 400 mg of iodized oil are recommended.
  • For radiation emergencies: Potassium iodide (KI) should be taken just prior to, or as soon as possible after, exposure. Radiation is most harmful to pregnant or breastfeeding women and children, so KI is dosed according to amount of radiation exposure and age. Radiation exposure is measured in centigrays (cGy). For infants, babies, children, adolescents, and pregnant or breastfeeding women, KI is given if radiation exposure is 5 centigrays (cGy) or more.
    • For birth through 1 month, the dose is 16 mg of KI.
    • For babies and children over 1 month through 3 years, 32 mg.
    • For children 3 to 12 years, 65 mg.
    • For adolescents 12 through 18 years, 65 mg or 120 mg if the adolescent is approaching adult size.
    • For pregnant or breastfeeding women, 120 mg.
    • For adults 18 to 40 years with exposure to 10 cGy or more, 130 mg of KI is given.
    • For adults over 40 years with exposure to 500 cGy or more, 130 mg of KI is given.
  • For thyroid conditions:
    • For thyroid storm: Five drops of a saturated solution of potassium iodine every 6 hours is recommended.
    • For reducing the size of thyroid nodules: Iodized salt 150-200 mcg daily in addition to thyroxine 1.5 mcg per kg daily after surgery for benign nodular thyroid disease, or 50-100 mcg/day based on needs, for up to 12 months.
  • For painful fibrous breast tissue (fibrocystic breast disease): Molecular iodine 70-90 mcg/kg for 4-18 months.
  • For breast pain (mastalgia): Iodine 3000-6000 mcg daily for 5 months.

ON THE SKIN:

  • For venous leg ulcers: Topical application of cadexomer iodine to venous leg ulcers for 4-6 weeks. Also, solutions containing 10% povidone-iodine, ointment containing 10% povidone-iodine, and dry powder spray containing 2.5% povidone-iodine have been used in combination with compression therapy.
  • For diabetic foot ulcers: Topical iodine 0.9% ointment for 12 weeks.
  • For mouth sores (oral mucositis): 100 mL of a mouth rinse containing povidone-iodine solution used as a rinse for 3 minutes four times daily starting at the beginning of radiotherapy and continuing until one week after radiation is completed.
  • For gum inflammation (periodontitis): A rinse with 0.1% to 10% povidone-iodine used during scaling and root planing.
  • For surgery: Spray containing iodine in the form of povidone-iodine has been applied before and after wound closure. Also, solution containing 0.35% to 10% povidone-iodine has been applied for one to three minutes before or after wound closure.
  • Swelling of the uterine lining (endometritis): A vaginal wash containing iodine in the form of povidone-iodine 1% to 10% has been used immediately before Cesarean delivery.

CHILDREN

BY MOUTH:

  • For iodine deficiency: Consumption of iodized salt is recommended in most cases.
    • For most people, iodized salt containing 20-40 mg of iodine per kilogram of salt is recommended. If salt consumption is less than 10 grams per person per day, the amount of iodine in salt may need to be higher.
    • In children aged 7 months to 2 years, iodine supplementation may be necessary if iodized salt is not available. In those cases, supplements providing 90 mcg of iodine daily or a single annual dose of 200 mg of iodized oil is recommended.

AS EYE DROPS:

  • Conjunctivitis: Eye drops containing 2.5% povidone-iodine given shortly after birth.

The National Institute of Medicine has set Adequate Intake (AI) of iodine for infants: 0 to 6 months, 110 mcg/day; 7 to 12 months, 130 mcg/day.

For children and adults, Recommended Dietary Amounts (RDA) have been set: children 1 to 8 years, 90 mcg/day; 9 to 13 years, 120 mcg/day; people age 14 and older, 150 mcg/day. For pregnant women, the RDA is 220 mcg/day, and breastfeeding women, 290 mcg/day.

Tolerable Upper Intake Levels (UL), the highest level of intake that is not likely to cause unwanted side effects, for iodine intake have been set: children 1 to 3 years, 200 mcg/day; 4 to 8 years, 300 mcg/day; 9 to 13 years, 600 mcg/day; 14 to 18 years (including pregnancy and breastfeeding), 900 mcg/day. For adults older than age 19 including pregnant and breastfeeding women, the Tolerable Upper Intake Level is 1100 mcg/day.

Safety Concerns

Iodine is LIKELY SAFE for most people when taken by mouth at recommended amounts or when applied to the skin appropriately using approved products.

Iodine can cause side effects in some people. Common side effects include nausea and stomach pain, runny nose, headache, metallic taste, and diarrhea.

In sensitive people, iodine can cause side effects including swelling of the lips and face (angioedema), severe bleeding and bruising, fever, joint pain, lymph node enlargement, hives, and death. However, such sensitivity is very rare.

Large amounts or long-term use of iodine are POSSIBLY UNSAFE. Adults should avoid prolonged use of doses higher than 1100 mcg per day (the upper tolerable limit, UL) without proper medical supervision. In children, doses should not exceed 200 mcg per day for children 1 to 3 years old, 300 mcg per day for children 4 to 8 years old, 600 mcg per day for children 9 to 13 years old, and 900 mcg per day for adolescents. These are the upper tolerable limits (UL).

In both children and adults, there is concern that 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, increased saliva, throat inflammation, stomach upset, diarrhea, wasting, depression, skin problems, and many other side effects.

When iodine is used directly on the skin, it can cause skin irritation, stains, allergic reactions, and other side effects. Be careful not to bandage or tightly cover areas that have been treated with iodine to avoid iodine burn.

Special precautions & warnings:

Pregnancy and breast-feeding: Iodine needs increase during pregnancy. Iodine is LIKELY SAFE when taken by mouth in recommended amounts or when applied to the skin appropriately using an approved product (2% solution). Iodine is POSSIBLY UNSAFE when taken by mouth in high doses. Do not take more than 1100 mcg of iodine per day if you are over 18 years old; do not take more than 900 mcg of iodine per day if you are 14 to 18 years old. Higher intake has been shown to cause thyroid problems in the newborn in some cases.

Autoimmune thyroid disease: People with autoimmune thyroid disease may be especially sensitive to the harmful side effects of iodine.

A type of rash called dermatitis herpetiformis: Taking iodine can cause worsening of this rash.

Thyroid disorders, such as too little thyroid function (hypothyroidism), an enlarged thyroid gland (goiter), or a thyroid tumor: Prolonged use or high doses of iodine might make these conditions worse.

Interaction with medication

Major
Do not take this combination.
Medications for an overactive thyroid (Antithyroid drugs)
Iodine can decrease thyroid function. Taking iodine along with medications for an overactive thyroid might decrease the thyroid too much. Do not take iodine supplements if you are taking medications for an overactive thyroid.

Some of these medications include methenamine mandelate (Methimazole), methimazole (Tapazole), potassium iodide (Thyro-Block), and others.

Moderate
Be cautious with this combination.
Amiodarone (Cordarone)
Amiodarone (Cordarone) contains iodine. Taking iodine supplements along with amiodarone (Cordarone) might cause too much iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid.
Lithium
Large amounts of iodine can decrease thyroid function. Lithium can also decrease thyroid function. Taking iodine along with lithium might decrease the thyroid function too much. Do not take large amounts of iodine if you are taking lithium.
Medications for high blood pressure (ACE inhibitors)
Some medications for high blood pressure might decrease how quickly the body gets rid of potassium. Most iodide supplements contain potassium. Taking potassium iodide along with some medications for high blood pressure might cause too much potassium in the body. Do not take potassium iodide if you are taking medications for high blood pressure.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), lisinopril (Prinivil, Zestril), ramipril (Altace), and others.

Medications for high blood pressure (Angiotensin receptor blockers (ARBs))
Some medications for high blood pressure might decrease how quickly the body gets rid of potassium. Most iodine supplements contain potassium. Taking potassium iodide along with some medications for high blood pressure might cause too much potassium in the body. Do not take potassium iodide if you are taking medications for high blood pressure.

The ARBs include losartan (Cozaar), valsartan (Diovan), irbesartan (Avapro), candesartan (Atacand), telmisartan (Micardis), and eprosartan (Teveten).

Water pills (Potassium-sparing diuretics)
Most iodine supplements contain potassium. Some “water pills” might also increase potassium in the body. Taking potassium iodide along with some “water pills” might cause too much potassium to be in the body. Do not take potassium iodide if you are taking “water pills” that increase potassium in the body.

Some “water pills” that increase potassium in the body include spironolactone (Aldactone), triamterene (Dyrenium), and amiloride (Midamor).

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.