― I am definitely not a henna expert but I have picked up a few things from the times that I have tried it.Before: -You CAN henna over chemically dyed hair but ONLY if the henna is 100% (BAQ) henna. Henna with any chemical salts or sands (called Compound Henna) will give you funky green hair. So if you decide to henna make sure its the good stuff. I've only used Jamila henna and I can vouch for them and say that their product is 100% the real deal. There are too different kinds, henna for hair [...].