Preventative or treatment?
A recent review of trials (Lancet Infect Dis 2007), confirmed that taking an effective Echinacea product can help PREVENT a cold as well as REDUCE its effects by as much as 58%, and the duration by 1.4 days if already suffering with a cold.
How does it work?
The alkylamides (which give your tongue a tingle sensation if taking a liquid Echinacea preparation), seem to be the key compounds responsible for the anti-inflammatory and immune modulating effects. Both Echinacea purpurea and Echinacea angustifolia contain high levels of alkylamides.
How much should I take?
A normal adult dosage for prevention is 2-3 gms of dried root equivalent/day. For treatment of an established infection, 3-5 times this doasge can be taken (in divided doses). If using a liquid preparation dispensed by your Naturopath, please be guided by their recommendation.
Does it interact with other drugs?
As with some herbs, there appears to be a "theoretical" potential, but in clinical settings (ie in practice), this cannot be extrapolated. A review in Mol Nutr Food Research in 2008 found NO evidence of verifiable reports of herb-drug interactions with any Echinacea product.
What about Quality?
This can be tricky unfortunately. In the past, when there have been independant reviews of Echinacea products in the retail market, the results have been disappointing (in terms of activity level). This can be due to companies using species that are similar but not exactly the ones we know to be useful, or the herb has been processed poorly, or they have not used the stems, roots and rhizomes, which we know to contain the highest levels of alkylamides. So I usually tell people to buy their herbal medicines from a Herbalist or Naturopath or to contact me regarding brands in the retail market that I think are up to scratch. Too many times I have patients say they took Echinacea (or Valerian or St John's Wort etc), which they purchased from the retail market, only to find them ineffective.
So BEFORE and DURING the winter months, keeps some good quality Echinacea handy and start dosing at the first sign of a cold. If you work closely with others (eg childcare, teaching, nursing, retail, hospitality) it may be worthwhile dosing daily throughout the season.