Vitex / Chasteberry (Vitex agnus-castus)

Tier 2 — promising · PMS · Cycle regulation · Prolactin

One of the best-studied herbs for PMS and menstrual cycle irregularity. The Schellenberg 2001 BMJ RCT (standardised Ze 440 extract) and the Ma 2014 meta-analysis found it significantly reduces PMS symptoms including breast pain, irritability, and mood swings. Works by modulating prolactin and dopamine. Takes 2 to 3 full menstrual cycles to see benefit. Do not use with hormonal contraceptives or fertility drugs.

Dose: 20–40 mg/day standardised extract (0.5% agnuside); allow 3 cycles for assessment