If I recall it was black henna that was said to be a carcinogen (and I would seriously question this, but anyway)so get the red henna - if it just says "henna" then it's red, which is the usual color for henna. Once you have washed the "paste" off it won't stain your clothing, it's your skin that will be stained for around ten days. But I've never had it rub off on my clothing. Sunbathing DEFINITELY helps psoriasis, although you're between the devil and the deep blue sea there since you're not supposed to get a suntan because it might lead to melanoma.