Chinese Chastetree (Vitex negundo) is sometimes used in traditional medicine for women's health, but the majority of scientific studies and clinical trials focus on Vitex agnus-castus (Chaste Tree or Monk’s Pepper), a related species. Vitex agnus-castus has moderate scientific evidence supporting its effectiveness in alleviating symptoms of premenstrual syndrome (PMS), particularly PMS Type H, which involves symptoms such as breast swelling and tenderness (mastalgia) due to fluid retention and hormonal fluctuations.

The proposed mechanism is that Vitex species may modulate prolactin levels via dopaminergic activity, thus reducing premenstrual breast pain and swelling. Randomized controlled trials and meta-analyses of Vitex agnus-castus have shown statistically significant improvements in PMS symptoms, especially mastalgia. However, there is limited direct research on Vitex negundo (Chinese Chastetree) for PMS Type H specifically. Some phytochemical and animal studies suggest anti-inflammatory and hormone-modulating properties, but human data are sparse. As a result, its use for PMS Type H is sometimes extrapolated from the more robust data on Vitex agnus-castus.

In summary, while the broader Vitex genus has some scientific backing for PMS relief, the direct evidence for Chinese Chastetree (Vitex negundo) in PMS Type H is limited, leading to a moderate (2/5) evidence rating.