I’ve used this specific formula of Yin Chiao for over 20 years. Take when you first begin to feel like you may be getting sick. Eat right and drink LOTS of water with it, and if you catch it soon enough (and your foundational health is not way out of whack), it will prevent you from becoming sick, nearly every time. If you were a bit too late or you balances were a bit too far off to start out with, it will at least lessen the severity of your illness, and you will have more energy as you are healing up.