It will damage and dry out your hair, making it feel like straw and you may get what my hairdresser sister likes to call a chemical cut, where the hair starts to break near the root leaving loads of tiny bits of hair. I've had my hair every color under the sun but just keep it natural now because color does damage your hair.
I color my hair often with various colors & my hair turned out shades I didn't like. Once I bough a medium brown color yet turned out natural black. I would recommend you try COLOR OOPS Hair Color REMOVAL. Try your local: CVS, Walgreens, or Wal-Mart. Good Luck
It will damage your hair a lot. It will be really dry and start to break. Once hair is damaged, that's it. There really is no fixing it. You can use products to help mask the damage and make it feel softer, but no matter what your hair will always be damaged. It could also cause your hair to fall out.
I would recommend waiting a while, and if you really don't want to wait, use a semi-permanent dye.