I think everyone has thier own thresholds. Biotion is water soluble so you can't really overdose, but some people stop taking it, or reduce the amount they are taking because of breakouts. I was taking a 5000mcg supplement, plus my hair supplement which contains 2000mcg, which was way to much for me and turned my skin upside down. Now I am just taking the hair supplement daily, and maybe take the 5000mcg once a week.