Skip to content

Coming soon. The store is not open yet.

Menu
Full Measure

Safety

Is iodine safe while breastfeeding?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

LactMed says breastmilk iodine follows what the mother takes in, and very high maternal intake, such as seaweed soup, can cause a temporary underactive thyroid in a breastfed baby. NIH lists 290 mcg a day while breastfeeding and an upper limit of 1,100 mcg. Ask your doctor before going beyond a prenatal vitamin.1,2,3

Key facts

  • LactMed reports that the iodine in breastmilk depends on how much the mother takes in.1
  • Excess maternal iodine, for example from seaweed soup, has been linked to a temporary underactive thyroid in breastfed infants, and a 3-year follow-up found no lasting thyroid problem.1
  • NIH lists 290 mcg of iodine a day while breastfeeding and an upper limit of 1,100 mcg for adults.2,3
  • LactMed says breastfeeding need not be interrupted after iodine-containing contrast medium, though one manufacturer advises a pause of 10 hours.4
  • Only about 19% of US breastfeeding women who took a supplement used one containing iodine, in 2011 to 2014 survey data.3

What does LactMed say about iodine in breastmilk?

LactMed calls iodine an essential trace nutrient and a normal component of breastmilk. It estimates infant needs at 15 mcg per kg of body weight daily for full-term babies and 30 mcg per kg for preterm babies, and says breastmilk iodine correlates well with the mother's urinary iodine.1

It gives the US recommended total intake while nursing as 290 mcg a day and the World Health Organization's as 250 mcg. It adds that the American Thyroid Association advises nursing women to take a daily supplement containing 150 mcg of iodine.1

In 2011 to 2014, 72.2% of pregnant women in the US took a dietary supplement, but only 17.8% took one containing iodine; among breastfeeding women the figures were 75% and 19%.3

LactMed also notes that vegan and vegetarian mothers appear to have lower iodine in their milk.1

Can too much iodine reach a breastfed baby?

LactMed says excessive maternal iodine near term and during breastfeeding, with seaweed soup as its example, can raise breastmilk iodine and cause transient hypothyroidism in breastfed infants. A follow-up at 3 years found no long-term thyroid problem in the infants exposed to high iodine in milk.1

In 96 seaweed and kelp products sold in Norway, supplements held 5 to 5,600 mcg of iodine per daily dose, labels were often inaccurate, and 54 products would exceed the upper limit in a single portion or dose.5

The potassium iodide prescription label says the drug is excreted in breast milk and that use by nursing mothers may cause skin rash and thyroid suppression in the infant. Ask your doctor before using kelp, seaweed or iodine-only products while nursing.6

Is iodine on the skin or in a nasal spray different?

For povidone-iodine, LactMed reports that use by a mother near term and during breastfeeding raises breastmilk iodine and can cause a temporary underactive thyroid in the baby, most of all in places where iodine is scarce. It says absorption through intact adult skin is minimal.7

LactMed's advice to clinicians is to minimize exposure by using lower concentrations, covering the smallest possible area, shortening contact time and avoiding repeat applications. It says to avoid douching with povidone iodine and iodine-containing tampons, and notes that iodine has not been measured in milk after the nasal spray. It adds that exposure near term can sometimes interfere with newborn thyroid screening tests.7

What about iodine contrast for a scan?

LactMed's entry for iohexol, an iodine-containing contrast medium, reports that maternal doses up to 45.3 g, which contain 21 g of iodine, produce low levels in milk. Because the agent is poorly absorbed by mouth, it is not likely to reach the infant's bloodstream.4

The manufacturer states that breastfeeding could be withheld for 10 hours, while guidelines from several professional organizations say breastfeeding need not be interrupted after contrast medium. LactMed lists other contrast agents in separate entries that this page did not read, so ask your doctor or the imaging team about your scan.4

Who should ask a doctor about iodine while breastfeeding?

  • Anyone with a thyroid condition or on thyroid medicine.3
  • Anyone who takes lithium or an antithyroid medicine, which the potassium iodide label says can add to iodide's effect on the thyroid.6
  • Anyone planning to use kelp, seaweed or an iodine-only supplement.5
  • Anyone about to have a scan with iodine contrast or to use iodine antiseptic on large areas, wounds or mucous membranes.4,7

Questions people ask

Is iodine safe during breastfeeding?

LactMed says excess maternal iodine can raise breastmilk iodine and cause a temporary underactive thyroid in a baby. NIH lists an upper limit of 1,100 mcg a day for adults. Ask your doctor before going beyond a prenatal vitamin.1,3

Is iodine contrast safe while breastfeeding?

LactMed says iodine contrast reaches milk in low amounts and is poorly absorbed by the infant, and that several professional organizations say breastfeeding need not be interrupted. The manufacturer of one agent advises a pause of 10 hours, so ask your doctor.4

Is iodine nasal spray safe while breastfeeding?

The sources checked do not address nasal iodine beyond LactMed's note that iodine has not been measured in milk after povidone-iodine nasal spray. That is not a finding either way, so ask your doctor or pharmacist.7

Can you take iodine while breastfeeding?

NIH lists 290 mcg a day as the need while nursing and 1,100 mcg as the upper limit. LactMed warns about very high maternal intake. Ask your doctor what your diet and vitamins already provide.1,2,3

Do I need to take iodine while breastfeeding?

NIH says breast milk iodine depends on the mother's intake. The American Thyroid Association advises a daily supplement with 150 mcg of iodine while nursing, and the American Academy of Pediatrics at least 150 mcg. Ask your doctor.2,3

See what we make

Every product shows its whole label and what its lab report covers. The store opens soon.

See the Full Measure line

Sources

  1. Drugs and Lactation Database (LactMed). Iodine. National Institute of Child Health and Human Development. Record updated September 15, 2026. Opened 2026-10-11.
  2. Office of Dietary Supplements, National Institutes of Health. Iodine: Fact Sheet for Consumers. Updated May 1, 2024. Opened 2026-10-07.
  3. Office of Dietary Supplements, National Institutes of Health. Iodine: Fact Sheet for Health Professionals. Updated November 5, 2024. Opened 2026-10-07.
  4. Drugs and Lactation Database (LactMed). Iohexol. National Institute of Child Health and Human Development. Record updated April 15, 2026. Opened 2026-10-11.
  5. Aakre I, Solli DD, Markhus MW, et al. Commercially available kelp and seaweed products: valuable iodine source or risk of excess intake? Food Nutr Res. 2021;65:7584. Opened 2026-10-07.
  6. Potassium iodide oral solution (saturated): prescribing information (Emerald Therapeutics). DailyMed, U.S. National Library of Medicine. Effective August 25, 2026. Opened 2026-10-07.
  7. Drugs and Lactation Database (LactMed). Povidone-Iodine. National Institute of Child Health and Human Development. Record updated April 15, 2026. Opened 2026-10-11.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.