For a great nail polish that won't kill your nails, one word: Zoya. Best polish brand out there. I also like Opi, but Zoya has fewer bad chemicals.
The worst product I ever used was Tarte Amazonian clay primer. That stuff made me break out with odd bumps under my skin on my entire face. Took 2 weeks to clear it completely. Makeup couldn't cover it because it was a texture problem, not color. It was humiliating to go to meetings!!
