Excellent, I give to family and friends who suffer from pollen allergies, unknown stomach viruses, cold and flu symptoms. When they take it multiple times daily as prescribed, it knocks it out in 1-2 days. I use it to prevent illnesses on occasional basis when those in my house or office are sick; it totally protects me. No sickness for me this entire flu season.
I keep a bottle handy ALL the time; I keep buying it because it works.