Can You Take Naltrexone While Pregnant?

If you just found out you're pregnant

1. Keep taking it until you have talked to your prescriber. Call this week, and tell your obstetrician or midwife you take naltrexone. Both labels ask you to report a pregnancy.^5,8
2. Know the risk of stopping. For opioid use disorder, untreated addiction in pregnancy is tied to low birth weight, preterm birth and fetal death.⁵ After stopping, a smaller opioid dose than you used before can be fatal (when the block fades). Tablets clear quickly, so relapse can follow within a short time if they are stopped without your clinicians knowing.^2,5
3. Ask what the plan is. The options are usually to stay on naltrexone or switch medicines. TIP 63, SAMHSA's guide for clinicians, says people who stop naltrexone and return to opioid use should be considered for methadone or buprenorphine.³

Starting and continuing are separate decisions

The opioid guidance (CDC and TIP 63) draws a line between beginning naltrexone during pregnancy and staying on a dose that was already working; the alcohol sources do not.

The sources agree on two points: data are limited, and the choice belongs to you and your clinicians.^3,4,7

What studies have found

No randomized trial exists. These are observational studies, most of them small.

The study groups chose their own treatment, and most included few people. In Towers, the women on naltrexone had chosen to fully detox from opioids during pregnancy, so they may differ from people who could not.^1,2

Naltrexone does reach the baby. Cord blood levels roughly matched the mother's: a median ratio of 1.11 on the shot and 0.74 on tablets in a 7-person study.¹¹ In Towers, levels were undetectable when naltrexone was stopped more than 60 hours before delivery.²

For opioid use disorder, methadone and buprenorphine come first

The CDC calls methadone and buprenorphine first-line for pregnant women with opioid use disorder and describes naltrexone's safety information in pregnancy as limited.⁴ The main obstacle to starting naltrexone is that it needs 7 to 10 days without opioids, and starting too soon can set off severe withdrawal.⁸ TIP 63 adds that supervised withdrawal during pregnancy is typically not advisable.³

A 2025 computer model of 100,000 hypothetical pregnant patients starting treatment in pregnancy (naltrexone after inpatient withdrawal) found buprenorphine gave the greatest lifetime benefit once infant outcomes were counted.¹⁶ Newborn withdrawal was less common with naltrexone in all 3 studies of it in a 2024 review, though the studies were small and most had a high risk of bias.¹ How the two medicines compare outside pregnancy is on naltrexone vs Suboxone.

Alcohol use disorder: guidelines disagree

The CDC's pregnancy guidance covers opioids only. For alcohol, the American Psychiatric Association's 2018 guideline recommends against medicines in pregnancy unless they treat withdrawal or another condition.⁶ A 2021 review weighed the harms of drinking in pregnancy and concluded naltrexone and acamprosate do not appear to carry substantial risk of birth defects. It also found little published safety evidence for any of them.⁷ The Vivitrol label lists growth restriction, facial abnormalities and impaired intellectual development among the harms of alcohol in pregnancy.⁵

In practice, few people get these medicines. In US insurance claims from 2016 to 2019, alcohol-medicine use among 2,080 people with alcohol use disorder fell from 12.1% before conception to 0.3% in the third trimester.¹⁷ In a separate claims study, 48 of 2,517 birthing people with an alcohol-related diagnosis (1.9%) received naltrexone; almost all alcohol medicines in the study were given after delivery.¹⁸ Other options are on naltrexone for alcohol use disorder and naltrexone vs acamprosate.

The Vivitrol shot in pregnancy

The Vivitrol label says data from published case series are insufficient to identify a drug-related risk of birth defects, miscarriage or other harm.⁵ For context, it gives the general US background risk: 2% to 4% for major birth defects and 15% to 20% for miscarriage.⁵ In animal studies of oral naltrexone, early fetal loss rose at 11 times (rats) and 2 times (rabbits) the human exposure; there were no malformations at much higher exposures.⁵

Each shot lasts about a month and can't be removed once given.⁵ In one Boston program, whether to move someone from the shot to tablets after 36 weeks was decided case by case, and naltrexone was avoided for 24 hours before delivery when possible. That was one hospital's own protocol.¹³

Labor, delivery and pain relief

Naltrexone blocks opioid pain medicines, so the delivery team needs to know you take it and when your last dose or shot was. Vivitrol's Medication Guide also asks you to carry a wallet card.^5,8

In the 7-pregnancy Boston series, everyone had an epidural that included fentanyl and delivered vaginally, with no pain-control problems reported. After delivery, acetaminophen, ibuprofen or ketorolac was enough. None had a cesarean, so the series does not cover pain control after surgery.¹³ General timing for stopping before procedures is on stopping naltrexone before surgery.

Breastfeeding

The Vivitrol label is inconsistent on breastfeeding:

• Section 8.2 (for prescribers): naltrexone and its main breakdown product, 6β-naltrexol, are present in human milk. It asks clinicians to weigh the benefits of breastfeeding against the mother's need for naltrexone and any risk to the baby.⁵
• Medication Guide (for patients): it is not known whether Vivitrol passes into milk, though naltrexone from tablets does. It says: "You should not do both."⁵

The generic tablet label says it is unknown whether naltrexone enters human milk and advises caution.⁸

We found two published measurements in breastfed infants. In 2004, one breastfed baby whose mother took oral naltrexone received about 1.06% of the mother's weight-adjusted dose and was healthy at 6 weeks.¹⁰ In 2026, one baby whose mother had the shot received 0.83%, which the authors describe as compatible with breastfeeding.¹¹ Two babies cannot show rare effects. UK guidance for health professionals from the NHS Specialist Pharmacy Service (2023) says naltrexone "can be used with caution during breastfeeding due to negligible amounts in breast milk," with the baby watched for drowsiness, weight gain and breathing problems; it notes that published evidence is very limited and that its advice covers healthy full-term babies.⁹ For alcohol use disorder, the APA guideline's recommendation against medicines covers breastfeeding too.⁶

What "pregnancy category C" meant

The generic tablet label still prints "Category C." Under the letter system FDA set up in 1979, prescription drug labels carried a letter: A, B, C, D or X.^8,19 For naltrexone tablets, the label pairs that letter with animal data (early fetal loss in rats at 5 times and rabbits at 18 times the human dose, and no birth defects up to 200 mg/kg a day), no adequate studies in pregnant women, and advice to use it only if the benefit justifies the risk.⁸

FDA's Pregnancy and Lactation Labeling Rule, published December 4, 2014 and in effect June 30, 2015, removed the letters.^19,20 FDA found the letters were misread as a grading scale, with risk rising from A to X, and gave the impression that drugs in the same category carried the same risk.¹⁹ Newer labels replace the letter with a written risk summary, clinical considerations and the underlying data, plus a lactation section. Vivitrol's label uses that format. For older-format labels, the rule required the letter to come off within 3 years of the effective date.^5,19,20

Trying to conceive

Tell your prescriber if you plan to become pregnant.⁸ The labels have only animal fertility data. In rats, a high oral dose raised pseudopregnancy and lowered pregnancy rates, with no effect on male fertility; the labels say the relevance to human fertility is not known.^5,8

Low-dose naltrexone (LDN) in pregnancy

LDN is an off-label use of naltrexone, often at 4.5 mg a day. A 2026 review found no evidence on whether the pregnancy concerns raised at 50 mg also apply at low doses. The same review describes one 350-person fertility study that reported higher pregnancy rates with LDN, but its methods were reported too thinly to judge.²¹ See LDN, pregnancy and other cautions.

Share your experience

Did you take naltrexone while pregnant or breastfeeding? Tell us what happened, or read other people's naltrexone reviews.

How we checked

• Sources: the current Vivitrol and generic tablet labels; full texts of Wachman 2024, Iannella 2026, Wachman 2019, Mantri 2024 and Roberts 2025; abstracts of the other studies; TIP 63; the CDC page; the APA guideline statements; NHS Specialist Pharmacy Service breastfeeding guidance; and the 2014 final rule.^3-6,8,9,19
• No randomized trial was found. Atluru 2024 reviews earlier cohorts, so it is not counted as extra data.
• Checked October 17, 2026: every figure, sample size and quoted line above.

Getting treatment

FindTreatment.gov, run by SAMHSA, lists treatment facilities and the medicines they offer.²²

SAMHSA's National Helpline, 1-800-662-4357, gives free, confidential treatment referrals 24 hours a day.²³