Pregnancy-induced nausea and vomiting

Overview

Vitamin B6 is the primary supplement studied for pregnancy-induced nausea and vomiting, with 10 trials. Most studies show it works better than placebo for reducing nausea and vomiting, though results vary and it appears less effective than ginger in direct comparisons. Common regimens include 25 mg every 8 hours for several days.

Professional guidelines recognize vitamin B6 as an option for nausea during pregnancy. For full trial details and dosing comparisons, see the heatmap and evidence reviews below.

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Vitamin B6	★★★★★	Medium

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Evidence Review

Taking vitamin B6 by mouth can help reduce nausea and vomiting during pregnancy for many people, although results vary.
Most studies show that it works better than a placebo, but not as well as ginger.
Taking 25 mg every 8 hours for 3 to 4 days can lessen nausea and vomiting.
Lower doses like 10 mg every 8 hours for 5 days help with nausea only.
A higher dose of 40 mg twice daily for 4 days works about as well as ginger 500 mg twice daily.
The American College of Obstetricians and Gynecologists (ACOG) recommends vitamin B6 at 10–25 mg three or four times a day as a safe first treatment for morning sickness.
However, for severe cases called hyperemesis gravidarum, vitamin B6 does not seem to help even when combined with extra medication and fluids.
Vitamin B6 is sometimes taken together with doxylamine (found in products like Diclegis or Bonjesta, approved by the FDA).
This combination is also considered a first treatment choice, but studies suggest the improvement is small—less than one point on a 13-point nausea scale.
In one study, only 41% of women taking vitamin B6 and doxylamine saw a meaningful improvement, compared with 92% taking ondansetron 4 mg.

Browse 10 studies2 meta-analyses

RCTAcupuncture and Doxylamine-Pyridoxine for Nausea and Vomiting in Pregnancy : A Randomized, Controlled, 2 × 2 Factorial Trial2023n=352

A randomized trial of 352 women found that compared with placebo, a higher risk for births with children who were small for gestational age was observed with doxylamine-pyridoxine (odds ratio, 3.8 [CI, 1.0 to 14.1]).

Effect: Benefit
Duration: 14 days
Population: Women
Participants: 352

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MetaThe effects of pyridoxine (vitamin B6) supplementation in nausea and vomiting during pregnancy: a systematic review and meta-analysis2023

A meta-analysis of 18 studies found that supplementation of pyridoxine alone as well as combined treatment of pyridoxine with an active ingredient as the intervention significantly improved the symptoms of nausea according to Rhode's score [0.78 [95% CI: 0.26, 1.31; p = 0.003; I2 = 57%, p = 0.10)] and PUQE score.

Effect: Benefit
Population: Women

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RCTA comparison between the effects of ginger, pyridoxine (vitamin B6) and placebo for the treatment of the first trimester nausea and vomiting of pregnancy (NVP)2018n=77

A randomized trial of 77 women found that 500 mg 2×/day ginger and vitamin B6 could reduce the severity of all items of Rhodes questionnaire significantly; however, placebo was significantly effective only on the frequency of nausea, intensity of vomiting and frequency of retching.

Effect: Benefit
Duration: 4 days
Dose: 500 mg 2×/day
Population: Women
Participants: 77

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ACOG Practice Bulletin No. 189: Nausea And Vomiting Of Pregnancy2018

A study in women found that safe and effective treatments are available for more severe cases, and mild cases of nausea and vomiting of pregnancy may be resolved with lifestyle and dietary changes.

Effect: Benefit
Population: Women

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RCTDoxylamine-pyridoxine for nausea and vomiting of pregnancy randomized placebo controlled trial: Prespecified analyses and reanalysis2018n=140

A randomized trial of 140 women found that 10 mg doxylamine + 10 mg pyridoxine, 2–4×/day for 14 days the active treatment was a tablet containing both doxylamine 10 mg and pyridoxine 10 mg taken between 2 and 4 times per day for 14 days depending on symptoms.

Effect: Benefit
Duration: 14 days
Dose: 10 mg doxylamine + 10 mg pyridoxine, 2–4×/day
Population: Women
Participants: 140
Ages: 18+

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MetaInterventions for treating hyperemesis gravidarum: a Cochrane systematic review and meta-analysis2017n=146

A meta-analysis of 146 studies found that there was insufficient evidence to identify clear differences between acupuncture and metoclopramide in a study with 81 participants regarding reduction/cessation in nausea or vomiting (risk ratio (RR) 1.40, 95% CI 0.79-2.49 and RR 1.51, 95% CI 0.92-2.48, respectively).

Effect: No Benefit
Population: Women
Participants: 146

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RCTOndansetron compared with doxylamine and pyridoxine for treatment of nausea in pregnancy: a randomized controlled trial2014n=36

A randomized trial of 36 women found that 25 mg pyridoxine + 12.5 mg doxylamine/day for 5 days there was no significant difference between the groups regarding sedation or constipation.

Effect: No Benefit
Duration: 5 days
Dose: 25 mg pyridoxine + 12.5 mg doxylamine/day
Population: Women
Participants: 36

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RCTComparison of the effectiveness of ginger and vitamin B6 for treatment of nausea and vomiting in early pregnancy: a randomized double-blind controlled trial2007

In 126 pregnant women with nausea, ginger 650 mg three times daily for 4 days was as effective as vitamin B6 25 mg three times daily for symptom relief.

Effect: Benefit
Duration: 4 days
Dose: 1950 mg/day
Population: Women

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RCTPyridoxine for nausea and vomiting of pregnancy: a randomized, double-blind, placebo-controlled trial1995n=342

A randomized trial of 342 women found that 30 mg/day for 11 months our purpose was to determine the effectiveness of pyridoxine for nausea and vomiting of pregnancy.

Effect: Benefit
Duration: 11 months
Dose: 30 mg/day
Population: Women
Participants: 342

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RCTVitamin B6 is effective therapy for nausea and vomiting of pregnancy: a randomized, double-blind placebo-controlled study1991n=59

A randomized trial of 59 women found that fifteen of 31 vitamin B6-treated patients had vomiting before therapy, compared with ten of 28 in the placebo group (not significant).

Effect: Benefit
Duration: 72 hours
Dose: 6 g/day
Population: Women
Participants: 59

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Evidence visualised

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Effect-size distribution

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Study distribution across 1 supplements for pregnancy-induced nausea and vomiting (nvp) (10 studies total).
Supplement	DEX	Studies	Meta-analyses	Share
Vitamin B6	★★★★★68%	10	2	100%

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Pregnancy-induced nausea and vomiting

Overview

Effect graph

Relevant supplements

Studies

Evidence visualised

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