Vitamin B6 for Nausea and Morning Sickness in Early Pregnancy

Vitamin B6 is one of the most commonly recommended supplements for nausea and vomiting in early pregnancy, and it has more research support than most other options in this category. That said, the evidence is rated moderate by the NIH Office of Dietary Supplements, not definitive, and personal dosing decisions should always involve a clinician.

What Is Vitamin B6 and What Does It Do?

Vitamin B6 is a water-soluble B vitamin that exists in several forms, the most biologically active of which is pyridoxal 5-phosphate (PLP). According to the NIH Office of Dietary Supplements, vitamin B6 acts as a coenzyme in more than 100 enzyme reactions, most of them involved in protein and amino acid metabolism. It also plays a role in the metabolism of carbohydrates and lipids, helps the body maintain normal blood homocysteine levels, and contributes to cognitive development through the biosynthesis of neurotransmitters.

These neurotransmitter-related functions are thought to be part of the reason researchers have investigated B6 in the context of nausea, though the precise mechanism during pregnancy is not fully established.

What the Evidence Shows for Pregnancy Nausea

The NIH Office of Dietary Supplements rates the evidence that vitamin B6 helps relieve nausea and vomiting in pregnancy as moderate. This places it above the limited or insufficient ratings assigned to many other proposed uses of the vitamin, but it is still short of the strong rating given to its well-established metabolic roles.

Moderate evidence means that clinical trials have shown promising results, but the body of research is not yet large enough or consistent enough to draw firm conclusions. It does not mean vitamin B6 is proven to treat or cure morning sickness. Supplements are not intended to diagnose, treat, cure, or prevent any disease, and these statements have not been evaluated by the FDA.

Reference Values During Pregnancy

The NIH Office of Dietary Supplements provides the following Dietary Reference Intake figures for vitamin B6:

• The Recommended Dietary Allowance for adults aged 19 to 50 years is 1.3 mg per day for both men and women who are not pregnant.
• The Tolerable Upper Intake Level for adults 19 years and older is 100 mg per day, applying to food and supplement intakes combined.

Note that the NIH ODS data provided here covers the general adult population. Pregnancy and lactation carry their own separate reference values, and a qualified healthcare provider can advise on the appropriate intake for your specific situation.

An Important Note on Upper Limits

The safety picture for high-dose B6 has become more nuanced in recent years. The NIH Office of Dietary Supplements notes that in 2023, the European Food Safety Authority set a considerably lower upper limit of 12 mg per day for all adults, including during pregnancy and lactation. This is substantially below the 100 mg per day figure set by the U.S. Food and Nutrition Board.

This gap reflects ongoing scientific discussion about where the true safe upper boundary lies. It is one more reason why choosing a dose on your own, particularly during pregnancy, is not advisable. A clinician or pharmacist can help you weigh current guidance against your individual health picture.

Safety Considerations

High intakes of vitamin B6 from food alone have not been reported to cause harm. However, the NIH Office of Dietary Supplements notes that long-term, high-dose supplementation can cause sensory neuropathy, a condition involving nerve damage that can produce numbness, tingling, or pain, typically in the hands and feet. This risk is associated with doses well above normal dietary intake, but it underscores why staying within recommended ranges matters, especially over extended periods.

Drug Interactions to Know

If you take any prescription medications, talk to your doctor before adding a vitamin B6 supplement. The NIH Office of Dietary Supplements identifies several clinically relevant interactions:

• Cycloserine (Seromycin): This antibiotic used for tuberculosis increases urinary excretion of pyridoxine and can worsen seizures and neurotoxicity. Pyridoxine supplements may help prevent these effects, but only under medical supervision.
• Antiepileptic drugs including valproic acid (Depakene, Stavzor), carbamazepine (Carbatrol, Epitol, Tegretol), and phenytoin (Dilantin): These medications increase the breakdown of vitamin B6 in the body, lowering plasma PLP levels and raising homocysteine. Separately, pyridoxine supplementation at 200 mg per day has been shown to reduce serum concentrations of phenytoin and phenobarbital, possibly by speeding up their metabolism, which could affect seizure control.
• Levetiracetam (Keppra): Preliminary evidence suggests vitamin B6 may reduce behavioral side effects such as irritability, agitation, and depression associated with this medication, but the evidence is early-stage and this should only be explored with a prescribing physician.

Other Proposed Uses and Their Evidence Ratings

For context, here is how the NIH Office of Dietary Supplements grades the evidence for other commonly discussed uses of vitamin B6:

• Reducing cardiovascular disease or stroke risk (alone or with folate and B12): Insufficient
• Cancer prevention or reduced cancer mortality: Insufficient
• Improving cognitive function or preventing cognitive decline in older adults: Insufficient
• Reducing symptoms of premenstrual syndrome (PMS): Limited
• Relieving nausea and vomiting in pregnancy: Moderate

This comparison helps illustrate that the nausea and pregnancy application has relatively more research support than most other proposed uses, while also making clear that no use of supplemental B6 currently carries a strong evidence rating outside its established metabolic roles.

Practical Takeaways

If you are experiencing nausea in early pregnancy and are considering vitamin B6, the most important step is to speak with your obstetrician, midwife, or another qualified clinician before starting any supplement. They can review your full health history, current medications, and dietary intake to recommend an appropriate approach. A pharmacist is also a reliable resource for questions about interactions and product quality.

Self-selecting a dose based on general internet information, including this guide, is not a substitute for personalized medical advice, particularly during pregnancy when both maternal and fetal health are involved.

Sources

• NIH Office of Dietary Supplements, Vitamin B6 Fact Sheet for Health Professionals: https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
• NIH Office of Dietary Supplements, Vitamin B6 Fact Sheet for Consumers: https://ods.od.nih.gov/factsheets/VitaminB6-Consumer/
• National Academies of Sciences, Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline: https://nap.nationalacademies.org/catalog/6015/dietary-reference-intakes-for-thiamin-riboflavin-niacin-vitamin-b6-folate-vitamin-b12-pantothenic-acid-biotin-and-choline