The prescribing information for naltrexone hydrochloride tablets (50 mg) says there are no adequate and well-controlled studies in pregnant women. It says naltrexone hydrochloride "should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus." On breastfeeding, it says whether naltrexone hydrochloride is excreted in human milk is unknown. No claim used here covers low-dose naltrexone in pregnancy or breastfeeding.
Which source this guide reports
This guide reports one source and gives no opinion on it: the label for the 50 mg tablet, with information updated September 4, 2026 on DailyMed. The label states the tablets are indicated in the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids.
The label passages used here do not mention low-dose use. Nothing used here says anything about low-dose naltrexone in pregnancy or breastfeeding, so this guide does not either.
Pregnancy: what the label says
The pregnancy section of the label for naltrexone hydrochloride 50 mg tablets states: "There are no adequate and well-controlled studies in pregnant women." It then states: "Naltrexone hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus."
Those two sentences report no human study results. No source used here reports a human study of naltrexone in pregnancy.
Animal data in the pregnancy section
The same section of the label gives two statements from animal studies. Both are animal data. They are not results in people.
| Question | What the source says |
|---|---|
| What did the label report for rats? | "Naltrexone has been shown to increase the incidence of early fetal loss when given to rats." |
| What did the label report for rats and rabbits given naltrexone orally? | "There was no evidence of teratogenicity when naltrexone was administered orally to rats and rabbits during the period of major organogenesis at doses up to 200 mg/kg/day." |
The label reports both findings. The statement on early fetal loss, as given here, names no dose. This guide does not compare the animal doses with any human dose.
Breastfeeding: what the label says
The nursing mothers section of the same label states: "Whether or not naltrexone hydrochloride is excreted in human milk is unknown." It continues: "Because many drugs are excreted in human milk, caution should be exercised when naltrexone hydrochloride is administered to a nursing woman."
What the label tells prescribers to say to patients
The information for patients section of the same label says to advise patients to notify their physician if they become pregnant or intend to become pregnant during treatment with naltrexone hydrochloride or are breast-feeding. This is the label's wording for the 50 mg tablet, and the passage does not mention low-dose use.
What this does not tell you
No claim used here covers low-dose naltrexone in pregnancy or breastfeeding. The label is for the 50 mg tablet, and the passages used here do not mention low-dose use. This guide cannot say whether any statement above does or does not apply to a low dose.
The statements used here give no rates or numbers for any pregnancy or breastfeeding outcome in people. The label's phrase "caution should be exercised" is the label's wording, and this guide does not explain what that caution would mean in practice. The label can be revised, and the date above is the version this guide reports.
The animal results are reported as animal data. This guide does not say whether they apply to people. The label says there are no adequate and well-controlled studies in pregnant women, and on human milk it says only that excretion is unknown.
This guide does not say whether a person who is pregnant, planning a pregnancy or breastfeeding should or should not take any form of naltrexone. The label says to advise patients to notify their physician. A licensed provider decides.