I have been using it as a topical treatment for myself and the kids for years with success. But I would never ingest it. If you overdose on it, it will turn your skin permanently blue. Google 'argyria images' and you'll see why.
Is that what happened to the people on Avatar? *innocent look*

I found colloidal silver at our local chemist, and it says the dose is 20ml a day or something (ingested), and the bottle didnt even say anything about just using topically, or that overdosing could result in permanent colour changes (that is kinda scary!).