How often can I use a semi-permanent hair dye?

What would happen if I were to use hair dye that's "for dark hair only" on blonde hair?

• Hiya. (: My hair's dark brown & I have the pieces that frame my face bleached blonde. What would happen if I were to use a hair dye that says it's for dark hair only on my entire head & the blonde pieces? It's a bright red dye. I've used that bright red hair dye in the past but my hair was all brown then & it did turn my brown hair red. That probably sounds like a silly question but would it just come out brighter on the blonde pieces than the brown parts or what? I hope I explained that okay hahaha. Thanks. :D

• Answer:

  My best guess would be that yes the hair dye would come out brighter on the blonde pieces than the brown because its stronger since its for dark hair only.