I use only henna on my hair. I buy mine from the stores with products from India. You can also get it online. Make sure you get only body art quality henna and henna that is the natural red brown henna color. Blue henna, black henna, etc has other chemicals that may clash with previously chemically colored hair and cause issues. For more info check out this site: Henna for Hair
. After reading that book I have used henna and had no problems.