You will lose the freshness, and the heat. Your beverage will separate, and since it will be cold it will not blend together as nicely as it did originally. I'd recommend picking up one of these:
as they are delicious cold, and adding some tasty high fat and protein lunch like a riceless sushi roll or sashimi. Guayusa has a nicely balanced xanthine profile and a non-jittery caffeine effect. Very tasty.
I find mine at Natural Grocers here locally. You can also find them at stores like Whole Foods and Sprouts. Hit up your local health food store, and note that some stores do not put them in their beverage coolers so check the bulk drinks section. Should be anywhere between $1.20 - $2.00. I prefer the berry flavor myself but it has a bit of sugar in it. Oh! Another excellent option are these:
these will be in the beverage cooler since they have to be kept cold. Also made with guayusa, and the chia seeds give a nice time released energy and omega-3s.