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Moderate evidenceWomen's health

Vitex (Chasteberry)

Vitex agnus-castus is one of the better-supported herbs for premenstrual syndrome and cyclic breast pain, but most positive trials come from a small number of manufacturer-linked research groups, so the true effect is probably smaller than the published numbers suggest.

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What the science says

  • Reduces premenstrual syndrome symptoms Moderate evidence

    A 2017 systematic review and meta-analysis identified 8 placebo-controlled RCTs of Vitex preparations in PMS, and all but one reported significantly greater symptom improvement with Vitex, typically over 3 menstrual cycles at 20-40 mg/day of dried extract. The authors flagged that the reported effect sizes were implausibly large, that most trials came from research groups linked to the manufacturers, and that risk of bias and publication bias were substantial — so the direction of effect is credible but the magnitude is not.

  • Relieves cyclic mastalgia (cyclical breast pain) Moderate evidence

    A 2020 systematic review and meta-analysis of randomized trials found Vitex preparations significantly reduced cyclical breast pain intensity versus placebo on visual analogue scales, with treatment typically over 2-3 cycles. Trials were small and heterogeneous in preparation (tinctures, 4 mg dry extracts, drops), and blinding quality varied.

  • Normalizes mildly elevated prolactin and luteal-phase defects Limited evidence

    Vitex diterpenes bind dopamine D2 receptors and can lower prolactin, and small trials in women with latent hyperprolactinemia reported shortened luteal phases normalizing and progesterone rising. These are old, small studies with inconsistent endpoints; Vitex is not a substitute for endocrine workup of hyperprolactinemia, which requires ruling out prolactinoma and drug causes.

  • Improves fertility or treats PMDD Limited evidence

    Fertility claims rest on a handful of small trials of multi-herb formulas, so the contribution of Vitex itself cannot be isolated. For premenstrual dysphoric disorder specifically, evidence is limited to small comparator trials against fluoxetine with no placebo arm — inadequate to recommend Vitex over established PMDD treatment.

Dosage & safety

Studied doseStandardized dry extracts at 20-40 mg/day are what most PMS trials used (Ze 440 at 20 mg/day, BNO 1095 at 40 mg/day), taken once daily in the morning for at least 3 consecutive menstrual cycles before judging effect. Mastalgia trials used similar extract doses or tinctures at roughly 30-40 drops daily. Benefit typically appears by cycle 2-3, not in the first cycle.
SafetyGenerally well tolerated; most common effects are nausea, headache, acne, itching and menstrual cycle changes including intermenstrual bleeding. Because Vitex is dopaminergic, avoid combining it with dopamine agonists (bromocriptine, cabergoline) or antagonists (antipsychotics, metoclopramide), where it may blunt or amplify effects. It may theoretically reduce oral contraceptive reliability and should be stopped during in-vitro fertilization or other hormonal fertility treatment unless a clinician approves. Avoid in pregnancy, and avoid in hormone-sensitive cancers (breast, endometrial) given unresolved endocrine activity. Not banned in sport, but as with any botanical, third-party-tested products are preferable.

How to take it

TimingOnce daily in the morning, every day including through your period, for at least 3 consecutive cycles.
With food?With or without food.
Worth knowingJudge it at cycle 3, not cycle 1 — benefit builds across cycles, and quitting after four weeks is the usual reason people conclude it does nothing.

Interactions

With medications

  • dopamine agonists (bromocriptine, cabergoline)

    Vitex is itself dopaminergic, so effects on prolactin may be amplified unpredictably. do not combine without medical supervision

  • antipsychotics and metoclopramide

    These are dopamine antagonists, and Vitex may blunt or interfere with their action. do not combine without medical supervision

  • hormonal contraceptives and fertility treatment

    It may theoretically reduce contraceptive reliability and interfere with controlled ovarian stimulation. stop during IVF or hormonal fertility treatment unless your clinician approves

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does vitex (chasteberry) help PMS?

Vitex has moderate evidence for PMS: in a meta-analysis, all but one of 8 placebo-controlled trials favoured vitex. Most trials came from manufacturer-linked groups, so the effect is probably smaller than published.

Does vitex help cyclical breast pain?

Yes, with moderate evidence: a 2020 meta-analysis found vitex reduced cyclical breast pain versus placebo over 2-3 cycles. The trials were small and used varied preparations.

How long does vitex take to work?

Take vitex at 20-40 mg/day of dried extract every morning for at least 3 consecutive cycles before judging it. Benefit typically appears by cycle 2-3, not in the first cycle.

Can vitex be taken with birth control or fertility treatment?

Vitex may theoretically reduce oral contraceptive reliability, and should be stopped during IVF or hormonal fertility treatment unless your clinician approves. Vitex is dopaminergic, so do not combine it with bromocriptine, cabergoline or antipsychotics without supervision.

Scientific references

Where to buy

Natural Factors, WomenSense®, Vitex Chasteberry Extract, 80 mg, 90 Vegetarian Capsules

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