Personally I would not. Not so much out of fear of poison but out of fear of bacteria.
(Anything that costs under $5.00 is not worth getting sick over.)
Call the toll free # on the bottle and let the bottling division of Starbucks know in case there is a larger problem. In all likelihood they will send you some complimentary coupons by mail for your inconvenience.
Then return it to the store where you purchased it and exchange it for a new one.
It could be spiked with a mind altering substance that would make you write things on Fluther that were totally grandiose and completely false. That may or may not be a bad thing, depending on your perspective. For now, don’t drink it.