P5P vs pyridoxine B6 for morning sickness

How do the options compare?

Options are compared on ACOG or MotherToBaby endorsement, size and quality of pregnancy-specific studies, dosing predictability, time-to-effect, and side-effect profile: the same axes an obstetric clinician would use.

• Pyridoxal 5' phosphate (PLP) is the active coenzyme form of vitamin B6, while most supplements contain pyridoxine hydrochloride and only some contain PLP. 1
• The delayed-release combination tested in the randomized placebo-controlled trial for nausea and vomiting of pregnancy used pyridoxine 10 mg per tablet alongside doxylamine 10 mg, taken as 2 to 4 tablets daily. 2
• In a secondary analysis, participants with the highest serum PLP levels had a 46% lower risk of persistent nausea and vomiting (HR 0.54), with a linear dose-response between PLP and time to remission. 3
• The prescription delayed-release product lists pyridoxine hydrochloride 10 mg per tablet, not pyridoxal 5'-phosphate, so the pharmacy version of this pairing is the plain B6 form. 4
• Doxylamine succinate paired with pyridoxine hydrochloride has been studied in hundreds of thousands of pregnancies without an increased chance of birth defects. 5

Which option makes sense?

A comparison can include options that should be avoided or considered only in specific circumstances. Please consult your healthcare provider about the findings and cautions that apply to you.

Disclosure: Pregnancy Smart makes supplements that overlap with some options above. This comparison describes the evidence, not our own product; where our formulation is relevant it is named.