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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.

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Drugs and Lactation Database (LactMed®) [Internet].

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Last Revision: November 30, 2022.

Estimated reading time: 1 minute

CASRN: 66108-95-0

image 135008074 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Limited information indicates that maternal doses of iohexol up to 45.3 grams (containing 21 grams of iodine) produce low levels in milk. In addition, because iohexol is poorly absorbed orally, it is not likely to reach the bloodstream of the infant or cause any adverse effects in breastfed infants. The manufacturer states that withholding breastfeeding for 10 hours after administration to minimize the exposure of the infant; however, guidelines developed by several professional organizations state that breastfeeding need not be disrupted after a nursing mother receives an iodine-containing contrast medium.[1-4]

Drug Levels

Maternal Levels. Four mothers who were 1 week to 14 months postpartum received iohexol by rapid intravenous injection. Three received a dose of 50 mL (37.8 grams; 17.5 grams of iodine) and one received 60 mL (45.3 grams; 21 grams of iodine). Milk samples of 10 mL were collected 9 times over the 48 hours after the injection. The average iohexol milk concentration over the first 24 hours was 24.6 mg/L in the 3 women 1 week to 4 months postpartum and 130.5 mg/L in the one woman who was 14 months postpartum and weaning her infant. The authors calculated that the average amount of iohexol received by the first 3 infants over the first 24 hours would be 3.7 mg/kg or 0.5% of the weight-adjusted maternal dosage.[5]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date.

Alternate Drugs to Consider



American College of Radiology Committee on Drugs and Contrast Media. Administration of contrast media to breast-feeding mothers. In, ACR manual on contrast media. 2022;Version 2022:106-7. https://www​.acr.org/Clinical-Resources​/Contrast-Manual.
Webb JA, Thomsen HS, Morcos SK, et al. The use of iodinated and gadolinium contrast media during pregnancy and lactation. Eur Radiol. 2005;15:1234–40. [PubMed: 15609057]
Chen MM, Coakley FV, Kaimal A, et al. Guidelines for computed tomography and magnetic resonance imaging use during pregnancy and lactation. Obstet Gynecol. 2008;112:333–40. [PubMed: 18669732]
Copel J, El-Sayed Y, Heine RP, et al. Committee Opinion No. 723: Guidelines for diagnostic imaging during pregnancy and lactation. Obstet Gynecol. 2017;130:e210–e216. [PubMed: 28937575]
Nielsen ST, Matheson I, Rasmussen JN, et al. Excretion of iohexol and metrizoate in human breast milk. Acta Radiol. 1987;28:523–6. [PubMed: 2960342]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Milk, Human

Contrast Media

Diagnostic Agents

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK501406PMID: 30000466


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