Hi Lucy. Given that you have had reactions since you were young, and especially since you get rashes as well as itching, you may well have an actual allergy rather than the kind of 'sensitivity' I was talking about. If the reaction were relieved by anti-histamines, that would also imply it was a more 'conventional' allergy. If it's an allergy, then skin tests from your doctor ought to show exactly what you're allergic to.
For me, with my itching, I don't get a rash. This experience is, according to two doctors I've discussed it with, "impossible". Nevertheless, it seems to be reasonably common...and I've had it for 15 years now...
Regarding "Bio-marked products" though, it was a pretty profound shock to read your thoughts about them. Back when I was discovering my problems with biological washing powder, I remember I was rather surprised by the sort of people who were using them. Several people who were "green" or "hippy" kind of mentality were using them, as I discovered as soon as I stayed over and slept in their spare beds. I was quite surprised that they would use bio powders - but your comments about a "green production process" etc give a strong hint why...
Biological detergents are so called because they add enzymes to conventional powders. The enzymes are harvested from micro-organisms, such as bacteria adapted to live in hot springs. They are "biological" in the sense that they are components of living things. Their biological action enables them to break down proteins, starches and fats, so they clean more effectively. But of course, with that extra power also comes extra risk.
It's a relatively new technology, and notwithstanding all the testing (on animals, mostly) that has gone into its safety approval, we are all still effectively human guinea pigs regarding the long-term effects of biological detergents. I easily came across quite enough evidence from discussing biological detergents with friends to feel fairly confident that adverse reactions are widespread.
The advertising for biological detergents has tended to be very misleading. I've seen biological detergents advertised in green packaging, with things like donations to green/animal charities advertised on the pack, all clearly to imply that they are a "green" solution of some kind. But they aren't at all; I don't have any evidence to point to regarding their environmental credentials but a bit of research on environmentalist web sites should reveal a bit of info about that, and my impression is that they are basically the worst kinds of detergents from a "green" point of view.
If you aren't getting reactions to certain bio detergents, I certainly wouldn't want to lecture you not to use them from a "green" point of view. Myself, I have so many sensitivities and dietary restrictions that I've had to abandon various ethical principles one by one in order to keep going - I don't know how I'd make it if I was still vegetarian for example. But it does seem strange that you are OK with bios but not with conventional detergents - the bios typically have everything that conventional detergents do, and the enzymes as well.
Basically I would recommend washing balls though: they have improved hugely in recent years and they are a good solution for me.
It would be well worth while doing some more web research on this subject - and post back here what you find out, if you like. I seem to remember finding a site, years ago, that helped me to identify and compare all the different 'ingredients' of various detergents, so in your case it would be interesting to compare the powders you've tried and maybe you could work out exactly what you're reacting to that way.
And if you come across contrasting scientific opinions about all this, I'd personally suggest taking any of the research that was funded by Proctor & Gamble or Unilever with a pinch of salt, eh? They have a slight conflict of interest...