Re: dyed hair an scalp psoriasis
I also dye my hair, and have a mild case of scalp psoriasis. I never found a shampoo that didn't strip the hair color, until recently.
I was at the local health food store, and bought Aubrey Organics shampoo. It has only natural ingredients, and no SLS - (which is irritating). I chose it because it was on sale. I was looking for an organic shampoo, and that's the one I ended up with. It has been great - my scalp feel wonderful, and my hair looks so much healthier - my co-workers even noticed.
As I mentioned, I have a 'mild' case, so this may not work for everyone. I think the key here is the 'natural' ingredients - not so much which brand you get. The shampoo and conditioner are very different consistency of anything I've used before, and it's making a difference for me.