Sorry, I seem to have edited out a sentence in my post. Olive leaf extract.
Go for the highest oleuropein content for the money. My usual dose is one 300mg (18% oleuropein) capsule at any first symptom for one to three days. If I get caught without any on hand or in a situation where is none available for a day or two (camping, etc.) and the symptoms develop into an actual cold or flu, I take two capsules the first day then one a day for the next three or four. The result is usually almost immediate, with almost all symptoms gone within 6 to 12 hours (overnight). For that sudden severe sore throat stuff ( the kind that leaves you unable to talk, swallow or even bend your head sharply downward within an hour or so of the first symptom) I usually take 2 capsules two or three times a day for a week or so. This usually clears it up to a point of tolerabillity within a day or so and completely in a few days ( last time this caught me, 5 or 6 years ago, I hadn't discovered the olive leaf and was acutely affected by it for over a month. it was awfull). If you're a herbal purist and avoid extracts, I suppose that the powdered leaf would also work, but a word of warning: The extract powder (and I assume the leaf powder) is the most horrible tasting stuff immaginable. It tastes so bad that it is unusable except in capsule form. I think the leaf powder would require a large volume of capsules to equal the oleuropein content of an extract capslue.
I would be interested in hearing form others who try this remedy. I know that everyones system is different and varying results would be expected (true of antibiotics as well) and wonder how many perople this works for as well as it does for me.