I have some sensitivities like that. Not all my sensitivities are natural, and not all are chemical either. Not all varieties of the following cause me to itch either. It varies. It's taken me YEARS to figure out what causes me problems. Trial and error have been my friend.
I'm sensitive to most artificial fragrances, lavendar, seaweed/algae, cones, sulfates, preservatives, and a host of other ingredients too. I think it depends for me on the quality of the ingredients. What I mean by this is that I can buy drugstore brands with the same ingredients as salon brands or online brands like my hg Curl Junkie that bother me, but in the better quality brands they don't. For instance, my head itches with most cones.....but the PEG modified one that Marsha uses in Curl junkie doesn't bother me. Nor do her fragrances (Garnier is a HORRID one for my itchy scalp. WAY too strong) either. When I do use full strength cones if I grab some brands they bother me, but when I use Kenra they don't. Same ingredient, better quality. Looking at the list of related chemicals to propylene glycol, I think I can add a mild sensitivity to those too, but again it depends on a lot (that probably explains why Paul Mitchell products bother me if I use them too often....they use a TON of the propylene glycol similar ingredients in their products).
I am an ingredient maven....I read all the ingredients of any product I try before I buy it. If I buy online and they don't list the full ingredient list I DON'T buy. I also buy from sites or stores that will take returns....I have had way too many times where I tried something I didn't think would bother me that did. I wish I could help you narrow it down, and I TOTALLY relate, but unfortunately for each individual it just boils down to trial and error. Some need longer times of trial and error than others. Like I said, it's taken me a long time to find out what bothers me.
My scalp and hair are different and their needs differ. I wanted to love CO washing but my scalp hated it while my hair was ok with it. So I went modified and looked for non sulfate shampoos, but some of them are as harsh or harsher on my hair and scalp than pure sulfates! I still occasionally need a sulfate shampoo so my hair doesn't get weighed down, but I've found a host of things I can use, and as long as it's only very occasional my scalp doesn't rebel.
In the long run what works for each individual varies, though. Wish I could help more.
Cosmetology Educator with sensitivities, eczema and Seborrheic Dermatitis.
Products: Free and Clear sulfate free poo and condish, Theraneem Sulfate Free Shampoo/Condish, Unscented SSCEJ, Coconut oil, Camellia oil, Argan oil
Lady Karaan, High Priestess of Hayr Tretements in the Order of Curly Crusaders
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