Re: sinus infection/ post nasal drip

I suggest something more like 20 PPM (no use for anything larger than that though), and I would take much more than a mere dropper full (and swallow it after holding it under the tongue).  What you really should do is to get a nasal sprayer and thoroughly irrigate your sinuses with colloidal silver a few times each day.

Pay no attention to advice to use single silver atoms - there is no product on earth which is actually made up of single silver atoms and no technology which can produce such a product.