i just pm'd you, but i'll reply here too.
i don't think you would have a problem using it, so long as you aren't allergic to the cassia plant. there are no additives to it. it's just the dehydrated, ground-up leaves into a powder.
i will add that there are pieces of twigs in there. you could sift them out before the application if you wish. i don't. the slip from my conditioner, in addition to the massage feature on my showerhead are enough to make them slide right on out and down the drain.
additionally, i use aubrey organics j.a.y. shampoo and j.a.y. conditioner to wash the henna out. these are awesome products.
i use their rosa mosqueta shampoo and conditioner during the warm/hot months, and change up to their jay shampoo and conditioner during the cool/cold months. both of these products are excellent for my coily/wavy/curly hair.