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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Urea C 14

Last Revision: August 17, 2020.

Estimated reading time: 1 minute

CASRN: 594-05-8

image 135267374 in the ncbi pubchem database

Drug Levels and Effects

Summary of Use during Lactation

Information in this record refers to the use of urea C 14 as a diagnostic agent. No information is available on the use of urea C 14 during breastfeeding. However, administration of urea C 14 directly to pediatric patients is considered to be safe.[1] International guidelines state that breastfeeding need not be interrupted after administration of urea C 14.[2]

Drug Levels

Carbon 14 is a low-energy beta emitter with a physical half-life of about 5730 years.[3]

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

Urea C 13


Pathak CM, Kaur B, Khanduja KL. 14C-urea breath test is safe for pediatric patients. Nucl Med Commun. 2010;31:830–5. [PubMed: 20864821]
Mattsson S, Johansson L, Leide Svegborn S, et al. Radiation dose to patients from radiopharmaceuticals: A compendium of current information related to frequently used substances. ICRP Publication 128. Annex D. Recommendations on breast-feeding interruptions. Ann ICRP. 2015;44(2) Suppl:319–21. PMID. [PubMed: 26069086]
Leide-Svegborn S, Ahlgren L, Johansson L, et al. Excretion of radionuclides in human breast milk after nuclear medicine examinations. Biokinetic and dosimetric data and recommendations on breastfeeding interruption. Eur J Nucl Med Mol Imaging. 2016;43:808–21. [PubMed: 26732471]

Substance Identification

Substance Name

Urea C 14

CAS Registry Number


Drug Class

Breast Feeding



Carbon Radioisotopes


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.


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