A natural herb used to increase milk flow for newly nursing mothers is "Blessed Thistle" capsules. It contains galactagogues which are described below. Blessed thistle has few side effects when taken in low doses over a short period of time. Blessed thistle should not be taken before the baby's birth.
A galactagogue is anything that excites lactation. In otherwords any thing that increases milk production. In humans common galactagogues are: caffiene, hops, fenugreek, fennel seed, blessed thistle, domperidone, alfalfa.
To decrease or stop milk lactation, the herb "Sage" can work well.