agnus castus shrub in the wild

Agnus castus: benefits, dosage, side-effects

Find out all about agnus castus, including what it does, the benefits of taking it and how much you might need

Written by Rosalind Ryan on December 28, 2018 Reviewed by Gabriella Clarke on January 8, 2019


What is agnus castus and what does it do?

Agnus castus – officially called Vitex agnus castus – is a shrub that grows in Mediterranean countries and central Asia. It is also known as chaste-berry, as eating the seeds was originally believed to reduce libido.1 The plant has been used for centuries to tackle female gynaecological issues and is still taken as a traditional herbal medicine to help relieve symptoms of premenstrual syndrome (PMS), such as irritability, mood swings, headaches, bloating and breast tenderness.2

Agnus castus berries are usually dried out, then made into either a powder (taken as capsules) or a tincture. It can also be used as an essential oil.

Benefits of agnus castus

What does agnus castus do in the body?

It’s not yet fully understood how agnus castus works, but it’s thought it has an impact on hormone-producing areas of the brain, such as the pituitary gland, which then leads to a reduction in prolactin, a hormone that may be involved in PMS.3 Agnus castus is most often taken for PMS, but research shows it may also be helpful for other hormonal conditions4 including menopause and female fertility issues:

PMS – a 2012 Iranian study found that agnus castus could offer relief from mild to moderate PMS symptoms, including headaches, depression and bloating,5 while German researchers reported in 2000 that the herb could reduce – and in some cases, entirely stop – PMS symptoms.6

Menopausal symptoms – according to a study published in the Journal of Alternative and Complementary Medicine in 2009, there is enough ‘emerging pharmacological evidence’ to recommend agnus castus as a way to manage menopause symptoms, particularly the PMS-like symptoms that occur during the perimenopause.7

An earlier 2003 study concluded that applying agnus castus essential oil to the skin could ease symptoms such as hot flushes, night sweats, sleep patterns and irregular periods.8

Fertility problems – thanks to its effect on prolactin, agnus castus could improve female fertility, particularly in women who have a shortened second-half of their menstrual cycle.9 Several studies have found that agnus castus can rebalance hormones and lengthen menstrual cycles, regulate periods and even lead to successful pregnancies.10

However, most of the research involved supplements that combined agnus castus with other vitamins or herbs, so further studies are needed to isolate its effects.


How much agnus castus is safe to take?

The European Medicines Agency suggests that 20mg a day of agnus castus is safe to take, to treat PMS. However, you should not take it for more than three months without advice from your GP or a healthcare professional, or if you’re pregnant or breast-feeding.11

 Side effects

What are the side-effects of taking agnus castus?

Some known side-effects of agnus castus include allergic reactions, such as swelling and difficulty breathing, headaches, nausea and stomach aches, and irregular periods.12 If you experience any of these side effects, stop taking agnus castus and seek medical attention – particularly if you’re having an allergic reaction. Because of the herb’s effect on the pituitary gland, those with a pituitary disorder should not take it without talking to their doctor first. If you're taking any other hormone medications, such as the contraceptive pill or hormone-replacement therapy (HRT), do not take agnus castus without proper medical advice from your GP or a healthcare professional.13 Shop Vitamins & Supplements Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies. Consumers, particularly those with allergies or intolerances, should read all product labelling, warnings and directions prior to use or consumption. Children should not take any licenced herbal medicinal products. 

1. European Medicines Agency. Assessment report on Vitex agnus-castus L., fructus. Available from:
2. European Medicines Agency. Agni casti fructus. Available from:
3. As above
4. Daniele C, et al. Vitex agnus castus: a systematic review of adverse events. Available from:
5. Zamani M, Neghab N, Torabian S. Therapeutic effect of Vitex agnus castus in patients with premenstrual syndrome. Available from:
6. Loch EG, Selle H, Boblitz N. Treatment of premenstrual syndrome with a phytopharmaceutical formulation containing Vitex agnus castus. Available from:
7. van Die MD, et al. Vitex agnus-castus (Chaste-Tree/Berry) in the treatment of menopause-related complaints. Available from:
8. Lucks BC. Vitex agnus castus essential oil and menopausal balance: a research update. Available from:
9. Alina Petre. Healthline. Vitex Agnus-Castus: Which Benefits of Chasteberry Are Backed by Science? Available from:
10. As above
11. As Source 1
12. As Source 2

13. As Source 1
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