Tonic Herbs are herbs that increase energy and strengthen the body. The effect of tonic herbs is to increase the strength of the muscular and nervous system while improving digestion and assimilation, resulting in a general sense of well-being.
Tonic: The tonic herbs strengthen and tone either specific organs or the whole body through nutritional stimulation.
Tonic - tonic herbs promote the various functions of the bodily systems. Most tonics have general effects on the entire body, but some also have more specific effects on particular organs or systems.
These are tonic herbs specific to the kidneys (source-gaines)