I've been snorting colloidal, well ionized, silver as soon as I feel a sinus infection starting. I simply don't know what a normal cold or flu feels like as mine always turn straight into a sinus infection either mixed with pneumonia or bronchitis. The silver definitely helps but I have to take it for at least 2 weeks to make sure the virus/ bacteria is gone. I also take wild Mediterranean oregano oil which I'm very impressed with. I am concerned about the accumulation of silver in my body though so I try not to over do it. I'm guessing once a year is safe, harsh winters in Quebec.