Last update Oct. 12, 2022

Naltrexone Hydrochloride

Very Low Risk

Safe. Compatible. Minimal risk for breastfeeding and infant.

It is a specific opioid antagonist with actions similar to, but more potent and longer lasting than, those of naloxone. It is used in the treatment of opiate dependence, alcohol dependence, and obesity. Intravenous and oral administration.

It is excreted in breast milk in clinically insignificant amounts and no problems were observed in a 6-week-old infant whose mother had been taking it orally since pregnancy. Plasma levels in this infant were very low or below the limit of detection. (Chan 2004)

Experts authors consider the use of this medication compatible during breastfeeding (Hale, LactMed, Briggs 2015) 

Until more published data is known about this drug in relation to breastfeeding, known safer alternatives are preferable (LactMed, Sachs 2013), especially during the neonatal period and in the event of prematurity.


Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Naltrexone Hydrochloride in other languages or writings:


Naltrexone Hydrochloride belongs to this group or family:


Main tradenames from several countries containing Naltrexone Hydrochloride in its composition:


Variable Value Unit
Oral Bioavail. 20 (5 - 40) %
Molecular weight 378 daltons
Protein Binding 20 %
VD 19.3 l/Kg
pKa 10.2 -
Tmax 1 - 2 hours
4 - 13 hours
Theoretical Dose 0.007 mg/Kg/d
Relative Dose 0.86 %


  1. LactMed. Drugs and Lactation Database (LactMed). Internet. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: 2006 - Consulted on April 16, 2024 Full text (link to original source)
  2. Hale TW. Medications & Mothers' Milk. 1991- . Springer Publishing Company. Available from Consulted on April 10, 2024 Full text (link to original source)
  3. Briggs GG, Freeman RK, Towers CV, Forinash AB. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. Wolters Kluwer Health. Tenth edition (acces on line) 2015
  4. Sachs HC; Committee On Drugs. The transfer of drugs and therapeutics into human breast milk: an update on selected topics. Pediatrics. 2013 Sep;132(3):e796-809. Abstract Full text (link to original source) Full text (in our servers)
  5. Chan CF, Page-Sharp M, Kristensen JH, O'Neil G, Ilett KF. Transfer of naltrexone and its metabolite 6,beta-naltrexol into human milk. J Hum Lact. 2004 Aug;20(3):322-6. Abstract

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