I don't think that semi-permanent dyes are damaging. At least, none of the vegetable based dyes that I've used, like Manic Panic. But if you want the tint to be vibrant, try Special Effects. It's like Manic Panic but the results are vibrant and last much longer. You can find them at punk.com and other websites too. I actually get mine from eBay. My hair is a vibrant deep red color right now and I love it! Well, hope I helped.