Sweet flag is considered to be one of the herbs of choice for rejuvenation of the brain and nervous system, but it is also used, in moderation, to tonify the appetite, digestive, and eliminatory systems. It is a vermifuge. This herb is also sometimes used to promote access to the unconscious.
The Ayurvedic Pharmacopoeia of India discusses the use of the dried rhizomes as a brain tonic in cases where there is weak memory, psychoneurosis and epilepsy. Some sources also refer to Vacha as an anti-stammering herb. Calamus is called "vacha" in Sanskrit. It is a rather complex herb with at 145 different chemical constituents. It reduces mostly vata as well as some kapha. This makes it both relaxing and decongesting.