Echinacea, its proper use
Echinacea is one of the herbs which should not be taken on a regular basis, because your system will become accustomed to it and it will lose its effectiveness. This includes all relaxants and the herbs with antibiotic type properties (with the exception of raw garlic, which does not appear to lose its effectiveness). Echinacea should only be taken when you really need it and then not longer than 10 days in a row.
All parts of the plant are effective. The fresher the herb, the higher the potency. You can tell if it is fresh if you feel the antiseptic property in your mouth. If you are growing the plant in your garden, you will want to preserve the roots and use the leaves and flowers for tea.
Echinacea stimulates the immune system. People with allergies and other immune system problems are usually disappointed with it. Their system is working at capacity most of the time and further stimulation has no effect. It may even be counterproductive.