How does Echinichea work?

This section of the Wikipedia entry on echinacea discusses some of the studies conducted on the plant's effectiveness in treating the common cold.
http://en.wikipedia.org/wiki/Echinacea#Studies

In short, most studies found it to be no more effective than a placebo but if it seems to work for you, then I don't think there's any medical harm in continuing to take it. The placebo effect can be quite powerful.

also, herbs don't necessarily work like western medicine (high dosage taken for a short period of time.) often, they need to be thought of like food, nourishing your immune system, etc. so it can fight for itself better.

It works just like all placebos. Danger: have you ever seen an echinacea addict?

have you ever seen a tylenol addict? medicinal quality doesn't have only to do with addiction.