What do medical sources say about Doxylamine (Diclegis) during pregnancy?

1st Trimester: MotherToBaby says studies of doxylamine with vitamin B6 did not find an increased chance of birth defects, but these findings are not doxylamine-only results. McKeigue et al. (1994) pooled 16 cohort and 11 case-control studies and reported a first-trimester relative risk of 0.95 (95% CI 0.88 to 1.04). In contrast, Bérard et al. (2019) found a small association with major birth defects in a Quebec cohort of 45,623 pregnancies exposed to the combination (adjusted odds ratio 1.07, 95% CI 1.03 to 1.11). These combination-product studies do not isolate doxylamine, and the cohort cannot establish cause. ACOG's FAQ, last reviewed in November 2025, says vitamin B6 may be tried first and doxylamine can be added if B6 alone does not ease symptoms. Ask your provider about your situation. 2nd Trimester: MotherToBaby reports no increased chance of preterm delivery or low birth weight in studies of doxylamine with vitamin B6, but it gives no separate second-trimester estimate. A small 2013 study found more late-preterm births with a higher-dose combination than with metoclopramide (5/28 versus 0/28; p=0.03); the low-birth-weight difference was not significant. A 2026 cohort included 345 doxylamine users, but its abstract reported overall outcomes for nausea medicines rather than a separate doxylamine estimate. A 2025 case report described fetal heart-rhythm changes at 23 weeks that resolved after doxylamine was stopped; one case cannot establish cause. ACOG's FAQ continues to list doxylamine with vitamin B6 as an option for pregnancy nausea. Ask your provider about your situation. 3rd Trimester: MotherToBaby reports no higher chance of behavior or learning problems among children exposed to doxylamine with vitamin B6, but its cited follow-up evidence is not doxylamine-only. The primary Nulman study followed 45 Diclectin-exposed children, 47 children with nausea and vomiting who did not take Diclectin, and 29 children without nausea and vomiting; testing took place at ages 3 to 7. A 2025 South Korean cohort included 1,383 doxylamine exposures among 630,904 children, but its abstract reported overall antiemetic findings and no separate doxylamine estimate. Neither study gives a distinct third-trimester result. ACOG's FAQ, last reviewed in November 2025, continues to list doxylamine with vitamin B6 as an option for pregnancy nausea. Ask your provider about your situation.

What do medical sources say about Doxylamine (Diclegis) while breastfeeding?

LactMed says small occasional doses of doxylamine would not be expected to cause infant effects, while larger or longer use may cause drowsiness, other effects, or lower milk supply. LactMed found no published doxylamine measurements in milk or infant blood. Morze et al. (2025) describe one 28-month-old child receiving 25% breastmilk while the mother used doxylamine and levothyroxine; the child had mild sleepiness, but the authors said their Naranjo assessment did not support a causal link. Ito et al. (1993) reported minor reactions in 8 of 85 infants exposed to maternal antihistamines, mostly irritability, but this was not doxylamine-specific. DailyMed says not to breastfeed while using Diclegis, while LactMed discusses occasional doxylamine doses and NHS SPS generally prefers non-sedating antihistamines for healthy, full-term infants. Ask your provider about your situation.

Where do sources disagree on Doxylamine (Diclegis) in pregnancy or breastfeeding?

First-trimester birth-defect findings for doxylamine-pyridoxine McKeigue et al. pooled 27 studies and found no increased overall malformation risk (relative risk 0.95, 95% CI 0.88 to 1.04). Health Canada's 2016 review said five meta-analyses found no increased risk and that most individual studies did not find a link. Bérard et al. reported a small association between first-trimester doxylamine-pyridoxine exposure and overall major congenital malformations (adjusted odds ratio 1.07, 95% CI 1.03 to 1.11), as well as several defect-specific associations. The studies used different populations, study designs, periods, and outcome groupings. The Quebec study was observational, so differences in the health and treatment of exposed people may contribute to its results. Both evidence groups concern combination products rather than doxylamine alone. The older pooled estimate and Health Canada's review are reassuring, while the later Quebec cohort reported modest associations. The available evidence does not establish cause or isolate doxylamine alone. Keep the compatible rating, but describe both findings and the combination-product limit.

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Doxylamine

Medication

Diclegis

Antihistamine

Pregnancy

Most pregnancy evidence concerns doxylamine with pyridoxine (vitamin B6), not doxylamine alone. MotherToBaby's March 2025 sheet says studies of hundreds of thousands of women did not find more birth defects, but its reference list does not provide a pooled participant count. McKeigue et al. (1994) pooled 16 cohort and 11 case-control studies of first-trimester Bendectin exposure, which involved doxylamine, pyridoxine, and in some studies dicyclomine. The pooled relative risk for any birth defect was 0.95 (95% CI 0.88 to 1.04). Bérard et al. (2019) studied a Quebec cohort with 45,623 doxylamine-pyridoxine exposures and reported an adjusted odds ratio of 1.07 (95% CI 1.03 to 1.11) for major congenital malformations. It also reported associations with spina bifida (aOR 1.87, 95% CI 1.11 to 3.14), nervous system defects (aOR 1.25, 95% CI 1.06 to 1.47), and musculoskeletal defects (aOR 1.08, 95% CI 1.02 to 1.14). These are observational data and do not establish that the medicine caused the outcomes. Ashkenazi-Hoffnung et al. (2013) compared 29 people treated with pyridoxine 50 mg twice daily plus doxylamine 25 to 50 mg daily with 29 people treated with metoclopramide. The combination group had 5 of 28 late-preterm births versus 0 of 28 in the comparison group (p=0.03); low birth weight was 3 of 28 versus 0 of 28 and was not statistically significant. This was a small, nonrandomized study using a higher regimen than the Diclegis tablet. Nulman et al. (2009) followed 45 Diclectin-exposed children, 47 children with nausea and vomiting but no Diclectin, and 29 children without nausea and vomiting. Children were tested at ages 3 to 7; the abstract concluded Diclectin did not appear to adversely affect brain development. MotherToBaby's miscarriage statement was not independently verified: its selected references do not identify an exposure-specific primary miscarriage study. In the past 12 months, a South Korean cohort included 1,383 doxylamine exposures among 630,904 children; doxylamine was a secondary exposure, and the abstract reports only the overall antiemetic result. A 2026 MotherToBaby Pregnancy Studies cohort included 345 doxylamine users among 603 people treated for nausea and vomiting; its abstract reports overall results and no doxylamine-specific estimate. This is not an independent check of MotherToBaby. A 2025 case report described fetal rhythm changes at 23 weeks during Unisom use that resolved after discontinuation; one case cannot establish cause.

Breastfeeding

LactMed's May 2025 record says small occasional doses would not be expected to cause adverse effects in breastfed infants, while larger or prolonged use may cause drowsiness or other infant effects or decrease milk supply, especially with pseudoephedrine or before milk supply is established. LactMed found no published maternal milk or infant blood levels for doxylamine. Ito et al. (1993) prospectively followed 838 infants exposed to maternal medicines; 8 of 85 infants in the antihistamine group had minor reactions, most often irritability. This was not doxylamine-specific. LactMed also mentions colic and drowsiness in its summary of mixed antihistamine reports, but Ito's abstract does not report those reactions for the antihistamine group. Morze et al. (2025) studied 200 breastfeeding women seeking pharmacist consultation. One table entry describes a 28-month-old receiving 25% breastmilk while the mother used doxylamine and levothyroxine; the infant had somnolence. The table gives Naranjo score 2, LCAT probable, and CTCAE grade 1, but the article says the Naranjo method did not support a causal link for any infant event. MotherToBaby says no studies assess the doxylamine-pyridoxine combination during breastfeeding. The DailyMed Diclegis label says women should not breastfeed while using it, while MotherToBaby notes a discussion of possible benefits and risks. No published doxylamine milk or infant levels were identified to estimate infant exposure.

First-trimester birth-defect findings for doxylamine-pyridoxine

Source A says: McKeigue et al. pooled 27 studies and found no increased overall malformation risk (relative risk 0.95, 95% CI 0.88 to 1.04). Health Canada's 2016 review said five meta-analyses found no increased risk and that most individual studies did not find a link. (McKeigue et al., Teratology 1994: Bendectin and birth defects meta-analysis, Health Canada: Summary Safety Review - Diclectin)
Source B says: Bérard et al. reported a small association between first-trimester doxylamine-pyridoxine exposure and overall major congenital malformations (adjusted odds ratio 1.07, 95% CI 1.03 to 1.11), as well as several defect-specific associations. (Bérard et al., Journal of Clinical Epidemiology 2019: Quebec Pregnancy Cohort)
Why they differ: The studies used different populations, study designs, periods, and outcome groupings. The Quebec study was observational, so differences in the health and treatment of exposed people may contribute to its results. Both evidence groups concern combination products rather than doxylamine alone.
Other sources: The current ACOG FAQ lists vitamin B6 and doxylamine as pregnancy nausea treatment options. The Diclegis label reports no increased risk for congenital malformations in epidemiologic studies. (ACOG: Morning Sickness FAQ, Nulman et al., The Journal of Pediatrics 2009: child follow-up)
What the evidence shows overall: The older pooled estimate and Health Canada's review are reassuring, while the later Quebec cohort reported modest associations. The available evidence does not establish cause or isolate doxylamine alone. Keep the compatible rating, but describe both findings and the combination-product limit.

Preterm birth findings for doxylamine-pyridoxine

Source A says: MotherToBaby reports that studies found no increased chance of preterm delivery or low birth weight after doxylamine-pyridoxine exposure. (MotherToBaby: Doxylamine succinate-pyridoxine hydrochloride, Medications for Nausea and Vomiting of Pregnancy and the Risks for Adverse Birth Outcomes, 2026)
Source B says: Ashkenazi-Hoffnung et al. reported more late-preterm births in a small combination-treatment group than in a metoclopramide comparison group (5/28 versus 0/28; p=0.03). The low-birth-weight difference was not significant. (Ashkenazi-Hoffnung et al., Israel Medical Association Journal 2013)
Why they differ: The 2013 study was small and nonrandomized, compared different nausea treatments, and used 25 to 50 mg of doxylamine daily with 100 mg of pyridoxine daily. This differs from the fixed-dose delayed-release product and does not isolate a drug effect.
Other sources: A 2026 MotherToBaby Pregnancy Studies cohort included 345 doxylamine users but did not report a separate doxylamine estimate in its abstract; it is part of the same initiative as MotherToBaby. (Medications for Nausea and Vomiting of Pregnancy and the Risks for Adverse Birth Outcomes, 2026)
What the evidence shows overall: This single small study is a signal that belongs in the summary, not proof of a cause. The broader cohort result is not doxylamine-specific. Keep the current rating and explain the limits.

Doxylamine while breastfeeding

Source A says: LactMed says small occasional doses of doxylamine would not be expected to cause infant effects, while larger or prolonged use may cause drowsiness, other effects, or lower milk supply. (LactMed: Doxylamine)
Source B says: The Diclegis label states that women should not breastfeed while using the combination product. MotherToBaby notes that the combination has not been studied during breastfeeding and repeats the label position, while also describing a possible benefit-risk discussion with a provider. (DailyMed: DICLEGIS label, MotherToBaby: Doxylamine succinate-pyridoxine hydrochloride, breastfeeding section)
Why they differ: LactMed discusses doxylamine, including small occasional doses; the label applies to the fixed-dose Diclegis combination. Direct milk-level and infant-level data are absent, so the sources weigh limited evidence and product-label precautions differently.
Other sources: NHS Specialist Pharmacy Service guidance last updated in February 2026 prefers non-sedating antihistamines for full-term, healthy infants and names chlorphenamine as its preferred sedating antihistamine; it does not make a doxylamine-specific recommendation. (NHS Specialist Pharmacy Service: Using antihistamines during breastfeeding)
What the evidence shows overall: The evidence is very limited and the label warning is stronger than LactMed's discussion of occasional doxylamine. Keep the guidance rating and two stars, state the difference clearly, and do not present the mixed-antihistamine findings as doxylamine-specific.

Last reviewed 2026-10-14

Independent check 2026-10-14

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Doxylamine

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