At a glance
- A 1999 systematic review of nine trials and 940 women found doses up to 100 mg a day eased PMS and depressive symptoms more than placebo.
- Daily dosing for two to three full cycles (around 80 mg a day) is the pattern with the most direct trial support.
- One trial used a tapering schedule: 80 mg daily the week before the period, then three times a week the rest of the cycle.
- No trial has tested a separate dose for PMDD specifically; the same range used for PMS was used in the one small PMDD subgroup studied so far.
- Doses far above trial amounts, taken for many months, have been linked to nerve symptoms like tingling or numbness.
Strength of evidence
Moderate evidence
A 1999 systematic review of nine trials (940 women) found vitamin B6 up to 100 mg a day eased PMS and depressive symptoms more than placebo, though trial quality was low. A 2020 pilot RCT found a similar effect at 80 mg a day. No PMDD-specific dosing trials exist.
What's the usual vitamin B6 dose for PMS?
Most clinical trials on vitamin B6 for PMS used daily doses between 40 and 100 mg, taken for one to three menstrual cycles.
A 1999 systematic review in BMJ pooled:
- Nine placebo-controlled trials
- 940 women total
- Doses up to 100 mg a day
The review found this eased overall PMS symptoms and depressive symptoms more than placebo ( [2]), though the authors noted most of the included trials were low quality.
| Trial | Daily dose | Length |
|---|---|---|
| BMJ systematic review, 9 trials, n=940 ( [2]) | Up to 100 mg | 1 to several cycles |
| Pilot RCT, n=72 completed ( [3]) | 80 mg | 3 cycles |
| Calcium plus B6 RCT, n=76 ( [4]) | 80 mg, split into two 40 mg doses | 2 cycles |
| Relaxation vs B6 RCT, n=150 ( [5]) | 80 mg | 1 cycle |
| Hypericum vs B6 RCT ( [6]) | 80 mg, two 40 mg tablets | 2 cycles |
None of these trials tested doses over 100 mg a day for PMS specifically, and the review found that going higher wasn't shown to work any better. For a wider look at whether the evidence holds up, see Vitamin B6 for PMS: does it work?.
Where this sits in your cycle
PMS window The week before your period
When should you take it, daily or only before your period?
Trials split into two approaches. Some dosed vitamin B6 every day of the cycle for two to three months, including the calcium combination trial and the Hypericum comparison trial ( [4], [6]). One trial used a tapering schedule instead: 80 mg a day for the week before the period, then three times a week for the rest of the cycle ( [5]).
No trial compared the two timings head to head, so the research doesn't say one approach beats the other. Many women choose to start supplements in the luteal phase, the one to two weeks before bleeding, since that's when symptoms tend to build and it's easier to remember a shorter window.
Niyora is a PMS and PMDD support app. If you want an estimated PMS window to help you time when to start, Niyora can show that without needing an account. PMS treatment: what actually helps covers how B6 fits alongside other options like calcium or CBT.
Can you take vitamin B6 every day?
Yes. Trials have tested daily dosing at around 80 mg for two to three full cycles without reporting serious problems ( [3], [4], [6]). That's the pattern with the most direct trial evidence behind it.
Whether a higher dose helps PMS hasn't been tested directly. A related 1997 trial gave women starting a low-dose birth control pill 150 mg of vitamin B6 a day for 30 days to see if it eased side effects like nausea and headache, and found no more improvement than placebo, suggesting that even at this higher dose, the effect was closer to placebo than a drug effect ( [1]).
A few practical notes if you're taking it daily:
- Take it with food to ease stomach upset.
- Take it at the same time each day so you don't double up or skip doses.
- Tell your pharmacist what else you take. B6 can interact with some medications, including ones for tuberculosis or Parkinson's disease.
None of the trials reviewed here tracked daily use past three months, so longer-term daily safety hasn't been directly tested in this group of studies.
What happens if you take too much vitamin B6?
The trials above tested doses up to 150 mg a day for short periods and didn't report serious harm. But taking much higher doses for many months has been linked, in research outside this list, to nerve symptoms: tingling, numbness or an unsteady walk, known as peripheral neuropathy. This usually eases once you stop taking it.
None of the PMS trials reviewed here tested doses anywhere near the range where those nerve symptoms have been reported. For a full list of side effects and when they tend to show up, see Vitamin B6 side effects, including mood.
Does the dose differ for PMS and PMDD?
None of the trials above enrolled only women with PMDD. One pilot trial included a small subgroup who met PMDD criteria and gave them the same 80 mg a day used for everyone else in the B6 arm. Their symptoms improved less than a broader micronutrient group, though the difference wasn't statistically reliable given how small that subgroup was ( [3]).
So current trial evidence doesn't support a separate vitamin B6 dose for PMDD.
PMDD is thought to be a different reaction to normal hormone shifts. That's part of why treatment guidelines focus on:
- SSRIs, sometimes taken only in the luteal phase
- Certain hormonal contraceptives
- CBT
A doctor decides what fits for each person. Supplements sit alongside SSRIs, certain hormonal contraceptives and CBT as options a doctor can weigh together. See PMS supplements: what actually helps, Vitamin B6 for PMDD: does it work? and Supplements for PMDD: what actually helps for more.
If you want to see whether a dose change lines up with calmer days, Niyora's estimated PMS window can help you spot the pattern.
From the research library
Research on vitamin B6
128 studies in the library look at vitamin B6 in PMS and PMDD. They were published from 1977 to 2026, and each one has a short summary of what was tested and found.
128
studies, 1977 to 2026
How strong the studies are
- Strong study design
- 11
- Moderate study design
- 55
- Early or limited evidence
- 62
Systematic review, 2025
Do nutritional interventions help with emotional symptoms of PMS?
Vitamin B6, calcium, and zinc consistently improved emotional PMS symptoms. Other nutrients like vitamin D, magnesium, and soy had insufficient evidence supporting their use.
Strong study design
Systematic review, 2013
Does Vitex (chaste tree) help PMS and PMDD symptoms?
Most studies found Vitex better than placebo for PMS. For PMDD, results were mixed: one study showed it equal to fluoxetine, while another found fluoxetine more effective. Side effects were mild.
Strong study design
Review, 2011
What are PMS and PMDD, and how common are they?
PMS affects 20-32% of women before menopause with moderate mood and physical symptoms. PMDD is more severe and affects 3-8% of women, causing significant problems at work or socially.
Strong study design
Systematic review, 2009
Which herbs, vitamins and minerals help treat PMS?
Only calcium has good evidence to work for PMS. Chasteberry and vitamin B6 may help, but most of the 62 products people try lack proper research.
Strong study design
Systematic review, 2007
What treatments work for premenstrual syndrome?
Many treatments have been studied for PMS, but researchers face a major challenge: there is no standard way to measure symptom severity, making it difficult to know which treatments truly work.
Strong study design
Randomised trial, 2003
What complementary and alternative medicines help with women's reproductive health issues?
Acupressure helps with pregnancy nausea and calcium helps with PMS. Vitamin B6, ginger, magnesium, chaste-tree berry, low-fat diet, exercise, and fish oil show promise but need more research.
Strong study design
Clinical trials
Questions people ask
What's the standard vitamin B6 dose for PMS?+
Vitamin B6 trials for PMS mostly used doses between 40 and 100 mg a day. A 1999 systematic review of nine trials in 940 women found doses up to 100 mg a day eased overall PMS and depressive symptoms more than placebo. No trial found that going higher worked better.
Is it safe to take vitamin B6 every day for PMS?+
Several trials gave women 80 mg of vitamin B6 every day for two to three menstrual cycles without reporting serious problems. Long-term daily use beyond a few months hasn't been directly tested in these PMS trials, so check with a pharmacist if you plan to take it for longer.
Can I take vitamin B6 only in the days before my period?+
Yes, one trial dosed vitamin B6 at 80 mg a day for the week before the period, then three times a week for the rest of the cycle. No study has directly compared that timing against taking it every day, so neither approach has stronger trial support.
What are the signs of taking too much vitamin B6?+
Taking far more vitamin B6 than trial doses, especially for many months, has been linked to tingling, numbness or an unsteady walk from nerve irritation, which usually improves after stopping. None of the PMS trials tested doses anywhere near that range.
Does PMDD need a different vitamin B6 dose than PMS?+
No trial listed here tested a PMDD-specific vitamin B6 dose. One pilot study included women who met PMDD criteria and gave them the same 80 mg a day used for PMS, with smaller improvement than a broader micronutrient blend in that small subgroup.
Sources
- 1.Effect of vitamin B6 on the side effects of a low-dose combined oral contraceptive, Contraception, 1997
- 2.Efficacy of vitamin B-6 in the treatment of premenstrual syndrome: systematic review, BMJ (Clinical research ed.), 1999
- 3.A Pilot Randomized Treatment-Controlled Trial Comparing Vitamin B6 with Broad-Spectrum Micronutrients for Premenstrual Syndrome, Journal of alternative and complementary medicine (New York, N.Y.), 2020
- 4.Effect of Combined Use of Calcium and Vitamin B6 on Premenstrual Syndrome Symptoms: a Randomized Clinical Trial, Journal of caring sciences, 2016
- 5.Comparison of the Effects of Relaxation and Vitamin B6 on Emotional and Physical Symptoms in Premenstrual Syndrome, DOAJ (DOAJ: Directory of Open Access Journals), 2015
- 6.Hypericum perforutum and Vitamin B6 as a Treatment for Premenstrual Syndrome, Jundishapur Journal of Natural Pharmaceutical Products, 2016