I thought I'd be unique in recommending Echinacea... but late as usual. Look, I'm one of those persons that inveterately maintains a journal... (pedantic, I know). Nearly 58 months ago, I began taking two to four capsules of Echinacea a day. Call it anecdotal, but in that time I've not had one cold or case of the flu.
As a life long commercial pilot, I along with a large majority of my colleagues, have experienced severe cases of sinusitis. In my case, three or four fairly major episodes a year. This had been treated with 10 day regimens of Augmentin XR (500mg), but I became concerned about the frequency of antibiotic treatment. A friend recommended Echinacea and on researching its effectiveness, I found enough support to at least try it. I'd admit to scepticisim. However, in the intervening 5 years, nothing else has been changed medicationally. Coincidence? possibly... but I'm going to keep taking it...
It is important to select a brand, either liquid, tea or capsules that are dependable for content and purity of the extract. I selected a brand known for its reputation and the capsules are 500mg each, taken two to three times daily. It seems taken in liquid or tea forms, higher dosages are required. Can't hurt, no?