I took a while to give my views on color treated and relaxed hair because I was not sure how my hair would end up reacting to it, now that I am seriously paying attention to its health. After five months of having my highlights in, however, I am now more confident that healthy, growing hair can be double processed with extreme care. To be honest the main way in which i stepped up my regime since getting highlights is simply being more consistent. I stopped experimenting as much as I have in the past and try to deep condition and co-wash at least once per week (each). So far, I do think my hair is not as thick as it has been in the past and I do not know if that has anything to do with the color. If I do not develop any excessive breakage, then I will definitely keep renewing my highlights yearly or so.
I am not sure if highlights are an option for everyone because I have read horror stories about using peroxide one day to wake up with half the hair on your head gone but do believe that can possibly be avoided, with a professional stylist and healthy hair. If your hair is already damaged, then obviously adding another harsh chemical will not help so I would say definitely wait till your hair is at its optimal health. I would also advise you to ensure you are getting your hair lathered in a really good conditioner at least twice weekly because the highlights are drying. Beyond that, once you have a solid regime and your hair is already doing well then maybe highlights really do not make that huge a difference or maybe they will actually slow me down. For now, who knows, all I can do is maintain my hair as best as possible and hope it continues to remain healthy even though it is double processed.