My doctor says try glucosamines if you wish, they seem to help some people, although there are no reliable tests on it yet.

Henna (Lawsonia inermis)- hope this works: henna
Acrobat necessary. The report gives a review of testing carried out on henna. The opinion is at the end of the technical article. "Lawsonia inermis 10% in petrolatum was considered non-iritating on human skin..." "Can be considered a weak sensitizer."
Nevertheless, "henna rot (red)contains 1-4 napthoquinone which appears to be a genotoxic chemical." Many tests are considered inqdequate. The opinion has the statement: "The present submission on Lawsonia inermis is inadequate."
If my link doesn't work, the site is: http://europa.eu.int/comm/food/fs/sc/sccp/out178_en.pdf