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Iobenguane I 131 use while Breastfeeding

Medically reviewed by Last updated on May 11, 2022.

Drugs containing Iobenguane I 131: Azedra

Iobenguane I 131 Levels and Effects while Breastfeeding

Summary of Use during Lactation

Information in this record refers to the use of iobenguane I 131 (I 131 meta-iodobenzylguanidine; I 131 MIBG) as a diagnostic agent. International agencies state that breastfeeding should be interrupted for more than 3 weeks following diagnostic use of I 131 MIBG.[1,2] After therapeutic dosages, the manufacturer recommends that breastfeeding should be withheld for 80 days after the final dose. These times usually result in permanent discontinuation of breastfeeding for this infant, and cessation of breastfeeding for the current infant is recommended by most experts.[1,3-5] Patients receiving iobenguane I 131usually receive potassium iodide prior to the diagnostic examination to block their thyroid gland’s uptake of the I-131 that is released from the I 131 MIBG. Iodide may interfere with the infant’s thyroid function.

Nursing mothers should not work with substances containing I 131 in their workplace.[6]

Drug Levels

I 131 is a beta and high-energy gamma emitter with a main gamma emission energy of 364 keV and a physical half-life of 8.04 days.[7] Iodide is actively secreted into breastmilk and actively taken up by the mother's and infant's thyroid glands.

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.


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. [PubMed: 26069086]
ARSAC notes for guidance: Good clinical practice in nuclear medicine. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2020. https://www​​/publications​/arsac-notes-for-guidance.
Bombardieri E, Giammarile F, Aktolun C, et al. 131I/123I-metaiodobenzylguanidine (mIBG) scintigraphy: Procedure guidelines for tumour imaging. Eur J Nucl Med Mol Imaging. 2010;37:2436–46. [PubMed: 20644928]
International Atomic Energy Agency. Radiation Protection and Safety in Medical Uses of Ionizing Radiation, IAEA Safety Standards Series No. SSG-46, IAEA, Vienna. 2018. https://www​​/publications/11102/radiation-protection-and-safety-in-medical-uses-of-ionizing-radiation.
Taïeb D, Hicks RJ, Hindie E, et al. European Association of Nuclear Medicine Practice Guideline/Society of Nuclear Medicine and Molecular Imaging Procedure Standard 2019 for radionuclide imaging of phaeochromocytoma and paraganglioma. Eur J Nucl Med Mol Imaging. 2019;46:2112–37. [PMC free article: PMC7446938] [PubMed: 31254038]
Almén A, Mattsson S. Radiological protection of foetuses and breast-fed children of occupationally exposed women in nuclear medicine - Challenges for hospitals. Phys Med. 2017;43:172–7. [PubMed: 28882410]
Dilsizian V, Metter D, Palestro C, et al. Advisory Committee on Medical Uses of Isotopes (ACMUI) Sub-Committee on Nursing Mother Guidelines for the Medical Administration of Radioactive Material. Final report submitted: January 31, 2019. https://www​​/ML1903/ML19038A498.pdf.

Substance Identification

Substance Name

Iobenguane I 131

CAS Registry Number


Drug Class

Breast Feeding



Iodine Radioisotopes

Diagnostic Agents

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