does certo work if someone did meth the night before?
Possibly, but it's a whole lot of trouble to go through all of the flushing and urinating just to pass a drug test. Keep in mind that Meth generally stays in the system for around 72 hours or more. Certo is more commonly used to mask the THC in marijuana, which isn't quite as potent as Meth. Also keep in mind that Certo has been known to fail if not used properly, and one would think that the odds of that would increase when using a more powerful drug. Either way, there is always the chance that it will not work at all.
I wouldnt say it would because Certo failed for me, but I was busted for pot. XD but you could try it I probly wont work.