If you are reacting to an infection using Colloidal Silver , your bodies immune system will have been exposed to the infection and will build immunities to it. In this case the Colloidal Silver is just speeding things along.
However, if you take Colloidal Silver every day, the infection may never register with the immune system and you wouldn't build up any immunity.
I seem to remember several people mentioning that after taking colloidal silver every day for an extended period of time, they caught a cold upon stopping the daily intake. You will have to check up on this.