Does anyone know if hair that's been treated (colored) with henna for years can be colored with a chemical hair color? My hair is titian red from using copper and red hennas for the last five years or so. It is also very long. My question is can I have my color dyed at a salon with chemical dyes now?

Permalia

www.hennaforhair.com might be able to help you.
It's going to depend on the kind of henna you used. There should be some info about that there. Perhaps in their FAQ.

If you layer henna-treated hair with conventional hair dye, you can sometimes get interactions with the chemicals and wind up with color shifts that were unanticipated.

Hopefully Lynne can say more, I just know I recall reading to avoid it.

I suggest that you don't use regular hair tint over henna. It can produce all kinds of interesting results - none of which will be what you planned.

someone I know dyed their hennaed hair and it went green :-S sorry!