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Agnus castus

Common names: Chaste tree, Monk’s pepper

Botanical name: Vitex agnus-castus

Parts used and where grown

Agnus castus grows in Mediterranean countries and central Asia. The dried fruit, which has a pepper-like aroma and flavour, is used in herbal medicine preparations.

Agnus castus has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings	Health Concerns
	Premenstrual syndrome
	Female infertility Fibrocystic breast disease
	Acne (associated with menstrual cycle) Amenorrhoea Dysmenorrhoea Endometriosis Menorrhagia (heavy menstruation) Pregnancy and postpartum support
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies)

Hippocrates, Dioscorides, and Theophrastus mention the use of agnus castus for a wide variety of conditions, including haemorrhage following childbirth and assisting with the “passing of afterbirth.” Decoctions of the fruit and plant were also used in sitz baths for diseases of the uterus. In addition, agnus castus was believed to suppress libido and inspire chastity, which explains one of its common names, chaste tree.

Active constituents

Agnus castus contains a few different constituents, including flavonoids, iridoid glycosides, and terpenoids. The whole fruit extract, rather than one of its individual constituents, appears to be necessary for the medicinal activity of agnus castus.¹ Agnus castus does not contain hormones. The benefits of agnus castus stem from its actions upon the pituitary gland—specifically on the production of a hormone called luteinising hormone (LH). This indirectly increases progesterone production and helps regulate the menstrual cycle. Agnus castus also keeps prolactin secretion in check.² ³ The ability to decrease mildly elevated prolactin levels may benefit some infertile women as well as some women with breast tenderness associated with premenstrual syndrome (PMS).

A controlled clinical trial found that women taking 20 mg per day of a concentrated agnus castus extract for three menstrual cycles had a significant reduction in symptoms of PMS, including irritability, mood swings, headache, and breast tenderness.⁴ Another double-blind trial found that women taking agnus castus had slightly greater relief from symptoms of PMS, including breast tenderness, cramping, and headaches, than those taking vitamin B6.⁵ These trials support the findings of preliminary agnus castus trials for women with PMS.⁶ ⁷ Agnus castus (32.4 mg per day), in combination with some homoeopathic remedies, has also been found in a double-blind trial to successfully treat breast tenderness (also called mastalgia).⁸

A review of other trials and case reports suggests there is at least preliminary support that agnus castus should be considered for women with irregular periods, infertility, and mildly elevated prolactin levels.⁹ Double-blind trials have confirmed the effectiveness of agnus castus at lowering mildly elevated prolactin levels in women.¹⁰ According to one small trial, acne associated with PMS, may also be reduced using agnus castus.¹¹

How much is usually taken?

The German Commission E monograph recommends a daily intake—30–40 mg of the dried herb—in capsules or in liquid preparations.¹² Agnus castus is typically taken once in the morning with liquid for a few months consecutively.

With its emphasis on long-term balancing of a woman’s hormonal system, agnus castus is not a fast-acting herb and is unlikely to give immediate relief to the discomfort associated with PMS. For premenstrual syndrome, frequent or heavy periods, agnus castus can be used continuously for four to six months. Infertile women with amenorrhoea (lack of menstruation) can remain on agnus castus for 12 to 18 months, unless pregnancy occurs during treatment.

Are there any side effects or interactions?

Side effects may include minor stomach upset and a mild skin rash with itching. Agnus castus is not recommended for use during pregnancy and should not be used concurrently with hormone therapy (e.g., oestrogen, progesterone).

At the time of writing, there were no well-known drug interactions with agnus castus.

References
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.