text: how long does cocaine stay in your system? how long does it take for about a gram of cocaine to get out of your system? my boyfriend did some last thursday and he has to take a drug test on wednesday for a job. how can u flush out ur system? he also did weed a couple weeks ago, will that show up in the test? how long a drug stays in you system is beside the point. what matter most is what kind of lab test will be performed to determine.  the drug itself can stay in your bloodstream up to 72 hours. however, most labs look for the metabolite, which is something that the body produces when it ingests something, in the case of cocaine it is "benzoylecgonine" that will stay around long after the drug is gone, up to 30 days for a frequent user.  if the lab prefer to take hair as a sample, cocaine can stay in your hair up to about 90 days. nevertheless, new information is becomming apparent suggesting cocaine stay's in your hair about 25 years - even after you have only taken it once.  and if you boyfriend has smoked weed, he definately don't have a chance. a minimum of thirty (30) days, minimum!  as medical science and employers become more and more aware of the problem exsisting in drug testing, they are choosing more complex, sophisicated testing methods. with these techniques and equipment, the only sure way to pass a test is to not do drugs and stay clear away from them.  hope this answers your question!