Monograph

Chasteberry

Q: Does chasteberry help PMS?

Probably, for some women. The EU accepts one specific extract, 20 mg a day, as a well-established PMS treatment after a placebo-controlled trial found that 52% of women on it had their symptoms at least halved, compared with 24% on placebo. Meta-analyses agree on benefit but warn that most trials are small and at high risk of bias. NCCIH calls the evidence low to moderate in quality.

Q: How long does chasteberry take to work?

Trials measured results after three menstrual cycles of daily use, and EMA recommends continued use over three months for the licensed extract. If symptoms persist after three months, or get worse, see a doctor. EMA advises against taking it for more than three months without medical advice.

Q: Can chasteberry relieve cyclical breast pain?

There is some evidence. A 2020 meta-analysis of six placebo-controlled studies found a moderate benefit at 20–40 mg a day for three months, but study quality was unclear. EMA did not approve it for breast pain because the trials were weak and breast pain should be diagnosed by a doctor. A new lump or one-sided pain always needs examination.

Q: Will chasteberry help me get pregnant?

There is no good evidence that it does. NCCIH says there is not enough reliable evidence for infertility, and EMA found the fertility studies too weak to support any claim. EMA does not recommend chasteberry in pregnancy, so stop as soon as you might be pregnant, and tell your fertility clinic if you take it.

Q: Does chasteberry help menopause symptoms such as hot flashes?

Not on current evidence. EMA found no controlled trials for menopausal symptoms, and MSKCC reports that chasteberry combined with St John’s wort did not relieve them. Black cohosh is the herb most studied for hot flashes, with its own mixed evidence and safety questions.

Q: Can chasteberry increase breast milk?

It should not be used for that. LactMed says no valid trials support it as a milk booster, high doses may lower prolactin and reduce supply, and it should be avoided while breastfeeding; EMA agrees. Fenugreek is the herb more often promoted for milk supply, though its evidence is also weak.

Q: Can I take chasteberry with the pill or hormone therapy?

Ask your doctor first. EMA says interactions with oestrogens and antioestrogens cannot be excluded, and MSKCC cites preclinical evidence that chasteberry may reduce the effect of contraceptives and hormone therapies. No contraceptive failures have been proven, but the question has not been properly studied.

Q: Is it true that chasteberry lowers libido?

That is the story behind its names. Ancient writers believed a potion of the plant reduced libido, and medieval monks reportedly used it to curb desire, hence monk’s pepper. Modern research has not tested this properly, and NCCIH says there is not enough evidence to know whether chasteberry affects sexual function either way.

Vitex agnus-castus

Updated October 4, 2026

Key points

01

One licensed PMS extract

The EU accepts a specific 20 mg daily extract as a well-established PMS treatment, based mainly on one placebo-controlled trial. Other products are traditional-use only.
02

Promising but biased evidence

Meta-analyses report large benefits for PMS and breast pain, but most trials are small and varied, at high risk of bias, and show signs of publication bias.
03

Works through prolactin

Lab studies show diterpenes acting on dopamine D2 receptors to curb prolactin release. In people the prolactin effect varies with dose and is not conclusively proven.
04

Not for pregnancy or breastfeeding

EMA does not recommend chasteberry in pregnancy or lactation, and animal data suggest it may suppress milk supply. Fertility claims rest on weak evidence.
05

Hormone and dopamine cautions

See a doctor first if you have a pituitary disorder or oestrogen-sensitive cancer, or take dopamine drugs, hormonal contraception, or hormone therapy.

Chasteberry, the fruit of the chaste tree, is one of the few herbs with a European licence for a specific women’s health complaint. In 2018 the EU’s herbal committee accepted one defined preparation, a 60% ethanol dry extract taken at 20 mg once daily, as a well-established medicine for premenstrual syndrome (PMS), largely on the strength of a single well-conducted placebo-controlled trial. Other chasteberry tinctures, extracts, and powders are accepted only as traditional remedies for minor symptoms in the days before a period. NCCIH, the US government’s complementary health centre, is more guarded: it describes the PMS studies as low to moderate in quality and says higher-quality evidence is needed.

The berries seem to act through the pituitary gland rather than the ovaries. Laboratory work has found compounds in the fruit that bind dopamine D2 receptors and suppress release of prolactin, the hormone that stimulates breast tissue and milk production, which is why chasteberry has been studied mostly for PMS and cyclical breast pain. The plant’s names preserve an older idea. Agnus and castus both mean chaste, and medieval monks reportedly used the peppery fruit to dampen sexual desire, which is where the name monk’s pepper comes from.

The limits matter as much as the promise. Most trials are small, test different products, and carry a high risk of bias, and the largest meta-analysis found signs of publication bias. Evidence for fertility, menopause, and acne is weak or missing. Because chasteberry acts on hormones and dopamine, it is not for pregnancy or breastfeeding, and anyone with a pituitary disorder, a history of oestrogen-sensitive cancer, or a prescription for dopamine drugs or hormones should speak to a doctor first. Nothing here is medical advice; severe premenstrual mood symptoms, a new breast lump, nipple discharge, or periods that stop need medical assessment rather than self-treatment.

In this monograph

01 The plant

Botanical profile

Vitex agnus-castus L. is a deciduous shrub or small tree native to Mediterranean Europe, central Asia, and parts of India (EMA). Older books place it in the verbena family, Verbenaceae; current classification puts it in Lamiaceae, the mint family, as EMA’s assessment notes. NCBI Taxonomy files it as taxon 54477 under the common name lilac chaste tree. The plant is aromatic, with hand-shaped (palmately compound) leaves divided into several slender, pointed leaflets. In summer it bears long, upright spikes of small lilac to violet flowers at the ends of the branches. These are followed by small, round, dark fruits with a pungent, peppery taste, the part used in medicine.

The European Pharmacopoeia defines agnus castus fruit as the whole, ripe, dried fruit and requires at least 0.08% casticin; its separate monograph for the dry extract requires at least 0.10% casticin, made with 40–80% ethanol (EMA). NCCIH notes that products on the US market may be made from the leaves, stems, flowers, and seeds as well, so a supplement labelled chasteberry or vitex is not necessarily the material tested in European trials. The clinical trials used named extracts: Ze 440, a 60% ethanol dry extract with a drug-to-extract ratio of 6–12:1 given as 20 mg a day, and BNO 1095, an ethanol extract given at a dose corresponding to 40 mg of fruit (He, 2009). Doses of different products are not interchangeable.

LactMed lists the fruit’s constituents as essential oils (limonene, sabinene, 1,8-cineole), iridoid glycosides (agnuside and aucubin), diterpenes (vitexilactone and rotundifuran), and flavonoids (apigenin, casticin, orientin, and isovitexin). Casticin (PubChem CID 5315263, C19H18O8) is the Pharmacopoeia’s quality marker, but the EU herbal committee states that no constituent with known therapeutic activity can be identified. The dopamine-active compounds isolated by Wuttke and colleagues (Phytomedicine 2003) are diterpenes, especially clerodadienols. EMA’s assessment reports that rotundifuran inhibited D2 receptor binding in the laboratory while aucubin and casticin did not, and that the flavonoids apigenin and penduletin showed oestrogen-receptor activity in one research group’s tests.

02 Lineage

History

EMA’s assessment report traces chasteberry to Dioscorides, the Greek physician and pharmacologist of the first century AD, and explains its doubled name: the Greek agnós and the Latin castus both mean chaste, and a potion of the plant or its seeds was believed to reduce libido. NCCIH adds that in the Middle Ages monks reportedly used chasteberry to decrease sexual desire, the origin of the names monk’s pepper and chaste tree, and that it was traditionally used for psychological illness, gynaecological disorders, and hormone-related skin conditions. Daniele and colleagues (Drug Safety 2005) list traditional uses for menstrual disorders, PMS, corpus luteum insufficiency, raised prolactin, infertility, acne, menopause, and disrupted lactation.

German-speaking Europe turned the berry into a modern medicine. EMA records chasteberry tinctures on the Austrian market from 1968 and tinctures and dry extracts in Germany from 1976, sold for irregular menstruation, PMS, and breast pain (mastodynia). Uncontrolled German reports from the 1950s and 1960s described chasteberry dilutions for absent or irregular periods and to support breastfeeding (EMA). Germany’s Commission E approved chasteberry for irregular menstruation, premenstrual complaints, and mastodynia, using ethanol extracts equivalent to 30–40 mg of fruit a day. Traditions do not always agree: LactMed notes that Persian traditional medicine used chasteberry to reduce an oversupply of breast milk, the opposite of the German breastfeeding claim.

The modern evidence base rests largely on Schellenberg’s placebo-controlled trial in the BMJ in 2001, which EMA later treated as the scientific basis for its well-established use, followed by a Chinese multicentre trial in 2009 and a dose-finding trial in 2012. The EU’s herbal committee adopted its first chasteberry monograph on 25 November 2010 and a revised version on 27 March 2018. That revision grants well-established use only to the Ze 440-type extract and traditional use to four other preparations that have been on the European market for more than 30 years. In Switzerland the licensed extract is described as the fruit of the monk’s pepper tree (EMA). In the United States chasteberry is sold as a dietary supplement, not an approved medicine (NCCIH).

03 Chemistry

Active compounds and how it works

EMA states plainly that chasteberry’s mode of action is not known. The leading hypothesis is dopaminergic. Laboratory studies summarized by EMA found that ethanol extracts of the fruit bind dopamine D2 receptors and inhibit prolactin release from rat pituitary cells, and that the lipophilic fraction carries this activity. Wuttke and colleagues traced this activity to clerodadienols and other diterpenes whose prolactin-suppressing properties were almost identical to dopamine’s. They proposed that premenstrual breast pain stems from latent hyperprolactinaemia, in which some women release excessive prolactin under stress and during deep sleep, and that dopaminergic compounds in the fruit relieve the breast pain and possibly other PMS symptoms.

Human data are less tidy. EMA notes that a reduction of raised prolactin by chasteberry in people has not been conclusively proven, and that the effect seems to depend on the dose and the starting prolactin level. In a crossover study of 20 healthy men, the lowest dose of 120 mg a day increased 24-hour prolactin secretion compared with placebo, while 240 and 480 mg decreased it; the authors suggested the extract contains both agonist and antagonist components. Volunteers reported dry mouth, slight confusion, disturbed perception, and other effects typical of dopaminergic drugs (EMA). LactMed likewise notes that low doses raise prolactin and high doses may lower it.

Other pathways have been proposed. EMA describes contradictory findings on oestrogen-receptor binding, binding of extracts to μ- and κ-opioid receptors in the laboratory, and a rise in β-endorphin in rats. MSKCC reports that casticin activates μ- and δ-opioid receptors in vitro, which may contribute to pain relief, and says chasteberry is thought to act on the pituitary-hypothalamic axis rather than directly on the ovaries. MSKCC also cites laboratory inhibition of the drug-metabolizing enzymes CYP2C19 and CYP3A4; EMA doubts this translates into clinically significant interactions.

04 In practice

Common uses

Premenstrual syndrome is the main use. Schellenberg (BMJ 2001) screened 178 women and evaluated 170 (86 on the extract, 84 on placebo) who took one Ze 440 tablet or a matching placebo daily for three cycles. Self-rated irritability, mood alteration, anger, headache, breast fullness, and other menstrual symptoms improved more with the extract (P<0.001), although EMA notes that bloating did not. Half or more of the symptom burden was relieved in 52% of women on chasteberry and 24% on placebo. In a follow-up dose trial, Schellenberg and colleagues (Phytomedicine 2012) randomized 162 women to 8, 20, or 30 mg of Ze 440 or placebo for three cycles: 20 mg beat both placebo and 8 mg, and 30 mg added nothing, which is why 20 mg became the licensed dose. He and colleagues (Maturitas 2009) tested BNO 1095 in 217 Chinese women with moderate to severe PMS over three cycles. The mean PMS diary score fell from 29.2 to 6.4 on chasteberry and from 28.1 to 12.6 on placebo, a significant difference, but the authors also recorded a placebo effect of about 50%. That large placebo response is typical of PMS research and is why EMA insists on placebo-controlled trials for this indication.

Reviews are positive but hedged. Verkaik and colleagues (American Journal of Obstetrics and Gynecology 2017) found 17 randomized trials, and 13 of the 14 they could analyse reported benefit. The pooled effect against placebo was large, but heterogeneity was extreme (I² 91%), most trials were at high risk of bias, and funnel plots suggested publication bias; the authors called the result explorative and probably an overestimate. Csupor and colleagues (Complementary Therapies in Medicine 2019) accepted only trials with properly characterized products. Just three of 21 trials, with 520 women, qualified, all using Ze 440 or BNO 1095; women taking chasteberry were 2.57 times more likely to have their symptoms remit than those on placebo.

Cyclical breast pain: Ooi and colleagues (Journal of Women’s Health 2020) reviewed 25 studies, 17 of them randomized. A conservative meta-analysis of six placebo-controlled studies with 718 women found a moderate effect favouring chasteberry, with typical doses of 20–40 mg a day for three months. Seven trials found it no worse than dopamine agonists, anti-inflammatory painkillers, antidepressants, or hormonal contraceptives, but the risk of bias in most studies was unclear. EMA did not accept breast pain as an indication, partly because studies lacked placebo controls or extract details, and partly because breast pain needs a doctor’s diagnosis. NCCIH likewise says chasteberry might reduce breast pain but better evidence is needed.

Fertility and other claims rest on weak evidence. NCCIH says there is not enough reliable evidence to know whether chasteberry helps infertility or sexual dysfunction, and notes it may be unsafe in pregnancy. EMA rejected a placebo-controlled trial in 52 women with short luteal phases because it relied on a prolactin stimulation test that EMA considers unreliable; the other luteal-phase studies were uncontrolled. In an observational study of Ze 440 for cycle irregularities, 12 of 53 women hoping to conceive became pregnant, but EMA notes that such a design cannot prove efficacy. EMA found no controlled trials for acne, menopausal symptoms, prolactinoma, or improving breastfeeding, and MSKCC reports that chasteberry combined with St John’s wort did not relieve menopausal symptoms. NCCIH mentions one low-quality study of heavy bleeding linked to an intrauterine device (IUD).

05 The apothecary

Preparations and traditional use

EU well-established use (EMA/HMPC/606742/2017, adopted 27 March 2018): dry extract (drug-to-extract ratio 6–12:1, extraction solvent ethanol 60% m/m), 20 mg once daily, for the treatment of PMS in adult women, as a tablet or other solid oral form. EMA recommends continued use over three months for an optimal effect and advises seeing a doctor if symptoms persist after three months of continued use. There is no relevant use before puberty, and use under 18 is not recommended because of a lack of adequate data. The 20 mg dose applies only to this specified extract; it does not translate to other products.

EU traditional use for minor symptoms in the days before menstruation, in adult women: powdered fruit, 400 mg twice daily (800 mg a day); tincture (1:5, ethanol 68–70%), 165 mg once daily; dry extract (7–13:1, ethanol 60% m/m), 4 mg once daily; or dry extract (10–18.5:1, ethanol 50–52% m/m), 2–3 mg once daily. Historical doses of the powder ran from 300 to 2,000 mg a day, but EMA capped it at 800 mg because its safety at higher doses had not been adequately addressed. Tinctures contain alcohol. EMA’s assessment concludes that chasteberry should not be taken for more than three months without medical advice.

Practical points: choose a product that names the plant part (fruit) and the extract, because US supplements vary and may include other plant parts (NCCIH). Trials judged results after three cycles, so a fair trial means three months of daily use, not occasional doses before a period. NCCIH notes that fruit extract has been used safely in research for up to three months. Keeping a daily symptom diary for two cycles before and during treatment helps distinguish PMS from other conditions; EMA notes that diagnosing premenstrual dysphoric disorder (PMDD), the severe form, requires prospective daily ratings. Stop at once if you become pregnant.

Safety

Before you use chasteberry

06 Caution

Side effects

Chasteberry is generally well tolerated in the short term. EMA lists severe allergic reactions with face swelling, difficulty breathing, and difficulty swallowing; allergic skin reactions such as rash and urticaria; acne; headache and dizziness; nausea and abdominal pain; and menstrual disorders, all of unknown frequency. Daniele and colleagues (Drug Safety 2005) pooled data from trials, post-marketing studies, surveys, spontaneous reporting schemes, and manufacturers, and found adverse events mild and reversible, most often nausea, headache, digestive upset, menstrual disorders, acne, itching, and red rash. NCCIH lists nausea, stomach pain, diarrhoea, headache, and itching.

In the BMJ trial only seven women reported mild adverse events, four on the extract and three on placebo, and none stopped treatment. EMA states that no serious adverse events were reported in any trial and that there were no documented severe adverse events apart from allergic reactions. At high doses, however, effects resembling those of dopamine drugs appear: in the study of 20 healthy men taking up to 480 mg a day, 18 reported 26 reactions, including dry mouth, disturbed perception, slight confusion, and itching in the mouth and nose (EMA). Changes in cycle length are also reported. LactMed notes that among 352 breastfeeding mothers given a chasteberry tincture there were 15 cases of itching, rash, or hives and some early returns of menstruation.

The liver and the ovaries are areas of uncertainty rather than established harm. EMA reports signs of liver toxicity in two repeat-dose studies in rats, lasting 4 and 26 weeks, and notes that tests for genotoxicity and carcinogenicity have never been done; for that reason it did not add chasteberry to the EU’s list of traditional herbal substances. NIH’s LiverTox, by contrast, says oral chaste tree has not been implicated in raised liver enzymes or clinically apparent liver injury in people. A 1994 report described disordered hormone levels and multiple follicles in a woman undergoing IVF who took a chasteberry product, but EMA notes the product also contained two other herbs, so chasteberry was never shown to be the cause.

07 Caution

Contraindications

Pregnancy and breastfeeding: EMA says there are no data on chasteberry in pregnant women, that animal studies are insufficient for reproductive toxicity, and that use in pregnancy is not recommended; it also notes that no fertility data are available. NCCIH says preclinical evidence suggests use during pregnancy may be unsafe. Anyone taking chasteberry while trying to conceive should stop as soon as pregnancy is possible or confirmed, and should tell their fertility clinic about it. EMA also does not recommend chasteberry while breastfeeding. It is not known whether its constituents pass into milk, and in a rat study the extract reduced the number of pups with milk in their stomachs, much like the prolactin-lowering drug bromocriptine (EMA). LactMed concludes that, because of concerning safety data and possible suppression of milk supply, chasteberry should be avoided during lactation, and that no scientifically valid trials support its use to increase milk.

Hormone-sensitive and pituitary conditions: EMA advises anyone who has or has had an oestrogen-sensitive cancer to consult a doctor first, because data on its oestrogen effects conflict; NCCIH says it may not be safe with hormone-sensitive conditions such as breast, uterine, or ovarian cancer, and MSKCC gives the same caution. Because it is thought to act on the pituitary-hypothalamic axis, EMA advises people with a history of pituitary disorders to see a doctor, and warns that in prolactin-secreting pituitary tumours chasteberry can mask symptoms. EMA’s assessment describes an 18-year-old whose pituitary microadenoma was found only after she had been taking chasteberry.

Other cautions: do not use chasteberry with a known allergy to it, and do not give it to anyone under 18, because adequate data are lacking and there is no relevant use before puberty (EMA). Severe premenstrual symptoms, especially marked depression, anxiety, or anger, may be PMDD, which has proven treatments; EMA’s assessment cites the Royal College of Obstetricians and Gynaecologists’ stepwise approach, which moves from lifestyle measures to drugs such as antidepressants or hormonal treatment. Missed periods, nipple discharge, breast lumps, and infertility all need investigation before any herbal treatment.

08 Caution

Drug and herb interactions

Dopamine drugs are the main theoretical concern. EMA says that because of chasteberry’s possible dopaminergic effects, interactions with dopamine agonists and dopamine antagonists cannot be excluded, and asks people taking them to consult their doctor first. Dopamine agonists include bromocriptine, used to lower prolactin, and many Parkinson’s medicines; antagonists include antipsychotics such as haloperidol and chlorpromazine and the anti-sickness drug prochlorperazine. MSKCC notes preclinical evidence that chasteberry might weaken these drugs or add to their side effects, and Daniele and colleagues concluded it might theoretically interfere with dopamine antagonists. No interactions have actually been reported in people (EMA).

Hormones: EMA also lists oestrogens and antioestrogens, which covers combined hormonal contraceptives, menopausal hormone therapy, and drugs such as tamoxifen. MSKCC cites preclinical evidence that chasteberry may reduce the effects of oral contraceptives and other hormone therapies, with clinical relevance not yet determined. If you rely on hormonal contraception, there is no proof that chasteberry makes it fail, but there is no proof that it does not. People undergoing IVF or ovulation induction should not add chasteberry without their clinic’s agreement, given the case report of disordered ovarian response. On drug metabolism, MSKCC reports that chasteberry inhibits CYP2C19 and CYP3A4 in vitro, which could in theory affect drugs broken down by those enzymes, including some antidepressants, statins, and immunosuppressants. EMA’s assessment considers it doubtful that this laboratory potential translates into clinically significant interactions. As with any supplement, tell your doctor and pharmacist that you take it.

09 Questions

Frequently Asked Questions