As with most dietary supplements, there is no well-established standard dosage for chasteberry, although general guidelines may be obtained from a few clinical trials.
(Click Chasteberry Dosage for more information.)
Theoretically, this product may interact with some medications (see Drug Interactions With Chasteberry).
It is not clear what exactly to expect from an overdose with this herb. If you think you or someone else may have taken too much chasteberry, it is important to seek immediate medical attention.
(Click Vitex Overdose for more information.)
Chasteberry contains a variety of different active compounds, such as essential oils and flavonoids. There are many different "active" compounds in chasteberry, and it is probably a combination of the compounds that is responsible for most of the medicinal properties of the plant.
This supplement seems to stimulate dopamine receptors, which indirectly inhibits the release of the hormone prolactin (a hormone involved in breastfeeding). However, this effect seems to occur with high doses of chasteberry; low doses appear to have the opposite effect on prolactin (causing an increase in the hormone). Chasteberry may also affect other receptors, such as acetylcholine and opioid receptors.
Chasteberry also appears to have effects on other hormones, such as estrogen and progesterone. While low doses may decrease estrogen levels, some compounds in the supplement may have estrogen-like properties. Low doses of appear to increase progestin levels. Interestingly, high doses do not seem to affect progesterone or estrogen levels.