Acidentily took too much nyquill?

ok so my brother thought he had the 15ml measuring cup, but he had the 30ml one, so he took 2 of the recommended dose, i dont really know what to tell him, heres the stuff he took a href="http://en.wikipedia.org/wiki/nyquil..." rel="nofollow"http://en.wikipedia.org/wiki/nyquil.../a he took the lquid kind, is he going to be ok, or should i tell him he needs to do something? oh and if it matters, hes 17, about 165 lbs and like 5ft 9in