Thought help: I had my hair professionally highlighted about a month ago. - Help.com

well, from my experience if you dye your hair all one color it might be all the same for a while but then the highlights will fade to a lighter color than the rest of you hair.

id go to the stylist and let them use a more powerful dye than you can buy at stores.

but that is just me, and whenever i dye my hair a darker color (whether if i do it myself or a stylist) it always fades quickly. (i even use color treated products :|)

If you imagine that the highlights are going to turn out a slightly lighter shade of the colour you dye your hair then you can see the final picture. The problem here is that if you use brown - they may turn out orange. I’d be very tempted this time to even go to a local hairdressing college (you only pay for the product so it’s very cheap). Also a strand test will need to be done on the highlights as, if they are blonde, they could turn green. This isnt a job for a home dye unless you are dyeing your hair very dark brown or black and even then the dye can ’slip’ off the highlights and you are left with an even worse result (orange). I’d seriously consider a tech college or back to the hairdresser - Regards Mas
p.s. As it’s nearly summer it may be worth letting your whole head of hair just catch the sun - the highlights would blend in much better and also if you dye it now you will be stuck with covering it up so it doesnt fade - and that is a lot of work wearing a hat constantly in the sun