Vitex (Chasteberry): What the Research Shows and Who Should Avoid It

Vitex, also called chasteberry or chaste tree berry, is the fruit of Vitex agnus-castus, a Mediterranean shrub sold as a supplement mainly for premenstrual symptoms. The research is mixed. Several small trials reported fewer premenstrual symptoms than with a placebo, but reviewers rate most of them as low to moderate quality, and there is little reliable evidence for fertility, menopause or other uses. Vitex is also not for everyone: it may be unsafe in pregnancy and while breastfeeding, and women with hormone-sensitive conditions or who take hormonal birth control, antipsychotics or Parkinson’s medicines should talk with a clinician first. Here is what vitex is, what the studies actually tested, the side effects and how to read a label.

Peptide Labs does not sell vitex or chasteberry products, so no product is recommended here. This article is general information, not medical advice.

What is vitex (chasteberry)?

The National Center for Complementary and Integrative Health (NCCIH) lists chasteberry, chaste tree, monk’s pepper and vitex as common names for the same plant, which is native to the Mediterranean and Central Asia. The name may reflect an old belief that the plant promoted chastity, and monks in the Middle Ages reportedly used it to lower sexual desire. Today it is promoted for premenstrual syndrome (PMS), breast tenderness linked to the menstrual cycle, infertility and menopause symptoms. Extracts can be made from the leaves, stems, flowers or seeds, but most clinical trials used extracts of the dried fruit.

How might it work? Lab studies summarized by Memorial Sloan Kettering Cancer Center (MSKCC) and the European Medicines Agency (EMA) suggest that compounds in the fruit act on the pituitary gland and hypothalamus and can lower the release of prolactin, a hormone thought to play a role in premenstrual symptoms. That is a lab mechanism, not proof of what happens in people, and it is one reason vitex can interact with medicines that act on dopamine.

Vitex benefits: what the premenstrual research shows

The most cited trial, published in the BMJ in 2001, followed 170 women in German community clinics for three menstrual cycles. Women taking a specific fruit extract (called Ze 440) reported larger drops in irritability, mood changes, anger, headache and breast fullness than women taking a placebo. About 52% of the vitex group improved by at least half, compared with 24% on placebo. Seven women reported mild side effects, four on vitex and three on placebo. It was one trial of one extract over three months.

Reviews put that result in context. A 2017 systematic review found 17 randomized trials, and 13 of 14 that could be analyzed reported a benefit. The pooled effect looked large, but the trials differed wildly, most had a high risk of bias and there were signs that negative studies went unpublished. The authors called the result merely exploratory and probably an overestimate. A 2019 meta-analysis kept only the three trials, with 520 women, that described their extracts properly. Women in those trials were about 2.6 times as likely as placebo users to report that their symptoms went into remission, but the authors noted that most vitex trials cannot count as evidence because of incomplete reporting.

Regulators reached a similar split verdict. The EMA’s herbal committee accepted one particular dry extract for premenstrual syndrome in adult women, used continuously for up to three months, based largely on that 2001 trial. It rated all other vitex preparations as traditional herbal medicines for minor premenstrual symptoms only, because their studies were poorly designed. In the US, vitex is sold as a dietary supplement, and the FDA does not approve supplements or their claims before sale.

Why the extract matters

The more positive results come from a few standardized extracts tested in Europe. Supplements sold in the US vary in plant part, extract strength and standardization, so a result from one extract may not apply to a different product. A powdered whole fruit and a concentrated extract are not interchangeable, even when both are labeled vitex agnus castus.

Chasteberry for menopause, fertility and other uses

NCCIH describes the evidence beyond premenstrual symptoms as thin. One preliminary study looked at menopause symptoms, there is not enough reliable evidence on infertility or sexual function, and early reports of antifungal effects come from lab work. Fertility marketing deserves extra caution: vitex may be unsafe during pregnancy, and someone trying to conceive could keep taking it in the first weeks before a pregnancy is confirmed. If you are trying to get pregnant, talk with your clinician before using any herb.

Vitex often shows up in “hormone balance” blends next to other ingredients with their own cautions. Our guides to the DIM supplement and maca root cover two common companions, and evening primrose oil is another herbal product marketed to women for similar reasons, with weaker evidence.

Vitex side effects and safety

NCCIH says chasteberry is generally well tolerated in the short term and that fruit extracts have been used safely in studies lasting up to three months. Reported side effects are usually mild: nausea, stomach pain, diarrhea, headache and itching. A 2005 systematic review of trials, surveys and spontaneous reports found adverse events were mild and reversible, most often nausea, headache, digestive upset, menstrual changes, acne, itching and rash. The EMA also lists rare severe allergic reactions with face swelling and trouble breathing or swallowing, plus dizziness. Stop and get medical help right away if swelling or breathing problems occur. Long-term safety beyond a few months is less studied.

Who should avoid vitex or ask first

• Pregnancy and breastfeeding: NCCIH says use may be unsafe, and MSKCC and the 2005 safety review advise avoiding it.
• Hormone-sensitive conditions: NCCIH says vitex may not be safe for women with conditions such as breast, uterine or ovarian cancer, and MSKCC notes its plant-estrogen activity.
• Hormonal birth control or hormone therapy: lab studies suggest vitex may weaken these medicines. The clinical relevance is unknown, so ask your prescriber.
• Antipsychotics and Parkinson’s medicines: because vitex appears to act on dopamine, MSKCC warns it may interfere with drugs such as chlorpromazine, haloperidol and prochlorperazine and with dopamine-agonist Parkinson’s drugs.
• Other medicines: lab data suggest possible effects on drugs processed by the liver enzymes CYP2C19 and CYP3A4. Show your pharmacist your full medication list.
• Teens: EMA monographs limit vitex medicines to adult women.

Herb-drug interactions are easy to overlook. Our St. John’s wort guide shows how serious they can become with another popular herb.

How to read a vitex label

1. Check the plant and part: look for Vitex agnus-castus fruit, the part used in most research.
2. Look for extract details, such as an extract ratio or a standardization statement, rather than an unnamed powder.
3. Watch for proprietary blends. They list only a total weight, not how much vitex is inside.
4. Read the rest of the ingredient list. Combination products add herbs with their own interactions.
5. Look for an independent quality seal. Our guide to third-party tested supplements explains what USP and NSF seals check.
6. Read front-of-pack wording such as “hormone balance” or “cycle support” as marketing that the FDA has not reviewed.

When to see a clinician instead

Premenstrual symptoms are common and usually mild, but the 2017 review notes that 5% to 8% of women have severe PMS, and clinicians have prescription options, such as certain antidepressants and oral contraceptives. See a clinician if symptoms disrupt work, school or relationships, if your periods stop or become very irregular, if you bleed between periods or after menopause, or if symptoms get worse or continue while you take an herb. For gut and vaginal health supplements marketed to women, see our probiotics guide.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed October 2026.

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