Sorry can't help about the rash but Deanne's point is a good one. Both my regular chemists promote generic (cheaper) brands when I get prescriptions filled. I don't take them because the active ingredients may be the same but the binders aren't and may cause different reactions. Sometimes the actual prescription doesn't suit, so you need to get something else prescribed but I wonder how many reactions are problems with generic substitutes? I'm a bit against chemists doing this, as it's a commercially driven offer.