Any hair experts about? Undoing henna advice needed

[Jackyjill6]

I have been told that I need to totally grow ou the henna in my hair before I can dye it a different colour. Is there any alternative.
?

No perm or semi-perm alternative. What you could do is use Indigo - but then you will face the same problem as Indigo definitely needs to be grown out before you do anything else.

You can apparently fade it somewhat with oil or colour b4. I've dyed over faded henna with artificial hair dye (had only done a couple of henna applications), and the artificial colour did fade quickly. But nothing dramatic happened. However you probably can't bleach it to blonde - it would likely still be orange.

Just to add, that's assuming 'proper' body art quality henna (or lush). Basically just henna plant.

What kind of henna was it?

I dyed over Lush red henna with brown dye and it was fine. I couldn’t lighten it though, but it was better than the ghastly bright orange it was.

I've dyed over in henna in the past. Years ago now. It was body shop henna. (Do they still sell it?) I don't remember a problem but I had let the henna fade quite a lot.

It was Lush henna. It was implied that there would be some sort of chemical reaction, or the result would be green.
I want to go blonde ideally.

I tried blonde hair dye on mine and nothing happened. It just dyed my roots blonde and the henna stayed the same. I had a hairdresser try and lighten it, but it was a complete mess all streaky orange. In the end, I just did a darker color until it grew out.

I don't think you can go lighter but you can go darker.