some people are allergic to silver gold or other metals in any form and should stay away from them. that is a possible explanation for above reaction. whether or not Colloidal Silver is toxic is of course a much debated subject. my own extensive personal experience leads me to believe that it should only be used in emergencies, and then followed by intensive recolonization of the intestinal flora. CS enthusiasts don't want to admit it, but CS destroy the good bacteria along with the bad, and the good bacteria is a key part of the immune defenses. that is why i like ozone, it does not destroy good bacteria from what i understand, if someone else has other knowledge about how ozone affects good bacteria i would be interested.