Quote Originally Posted by Hitcher View Post
I have seen the theory about sterile homes contributing to eczema, but not to hyper-allergies. Either has no supporting science of which I am aware.
The theory is along the lines of immune systems that aren't challenged by household 'bugs' don't develop normally and so then go into overdrive when challenged by substances that wouldn't otherwise be a problem. This sort of allergic response is normally delayed so different to immediate response allergic reactions (which often involve anaphylaxis), but can be serious with repeated exposures. Also eczema is considered an external version of asthma which is often part of an allergic response.

Introduction of some substances to infants' underdeveloped immune systems can also result in allergies to that substance (e.g. chocolate, peanuts, bovine milk) as is the case with my stepson who can't tolerate chocolate for this reason.