I have been drinking Ionic Silver Oxide for many years when I first started making Colloidal Silver (not now recommended, though). I never got any symptoms of Argyria, nor do I know of anyone who has, just from drinking Ionic Silver Oxide.
I have also been drinking true Colloidal Silver (the yellow/brown version) for fifteen years, and never had any symptoms of Argyria from this, either. There are two issues with intake of silver salts; the people who get Argyria (very very rare, I only know of three cases in the last twenty-five years) have all done the following:
i) They have drunk large amounts of silver salts such as silver nitrate, silver chloride or silver citrate. They have not been using true Colloidal Silver.
ii) They have not been makers of Colloidal Silver.
iii) They have mainly been trying to make an adverse point about Colloidal Silver and trying to destroy the reputation of Colloidal Silver making and Colloidal Silver itself.
I can't say it will never happen, but I don't know of anyone who has got Argyria from drinking therapeutic quantities of true Colloidal Silver. I hope this reassures you to a large extent.