Brahmi occupies an unusual position in the Ayurvedic pharmacy: it is classified as a medhya rasayana, a rejuvenative specifically for the intellect. The name derives from Brahma, and the association is with the faculty of understanding rather than with the body.
A note on naming, because it causes genuine confusion. Two different plants are sold as Brahmi — Bacopa monnieri and Centella asiatica, the latter also called Mandukaparni or Gotu Kola. They are used somewhat differently, and which one you have matters. It is worth reading the botanical name on the packet rather than the common one.
Traditionally it is taken over months rather than days. The classical framing is not of a substance that produces an immediate effect but one that, taken consistently, supports clarity, retention and steadiness of attention over time. This patience is characteristic of the rasayana category generally.
The common forms are the fresh juice, a powder taken with warm milk or ghee, or Brahmi ghrita, in which the herb is processed into ghee — a preparation intended to carry it into the deeper tissues. In Kerala and parts of Gujarat, Brahmi oil applied to the scalp at night is equally common.
It is cooling by nature and can be sedating at higher doses, so it does not suit everyone in every season. If you take thyroid medication or anything affecting the nervous system, raise it with your physician before starting.