Vaccaria segetalis (cowherb seed) is a dry mature seed of Vaccaria hispanica seeds. The seeds are used in Chinese medicine (Wang Bu Liu Xing) to increase milk supply orally as a decoction.[1-4] The seeds contain vaccarin, which has a prolactin-like effect on the mammary epithelial cells and increase the number of prolactin receptors in animal studies, as well as quercetin and oleic acid.[4,5] Vaccaria seeds may also have mild estrogenic activity.[5] No well-performed clinical trials have been reported in English on the galactogogue effect of Vaccaria seeds taken orally in humans. It has reportedly been used frequently with Liquidambar formosana (Lu Lu Tong) as a galactogogue combination known as Wang Bu Liu Xing and Lu Lu Tong herb pair (WLHP).[4]