I do not smoke marijuana but failed a drug test. i do take b complex daily and ibuprofin 400mg...

From what ?: Neither vitamins or ibuprofen will make you flunk a drug test. Chance ingestion of poppy seed muffins are a classic example where a common dietary item could trigger a false positive, this time to opiates (poppy) . You need to find out what agent caused you to fail and figure out how you might have been exposed.Just being in the same room with some weed smokers could make you flunk.

Could be ibuprofen: Ibuprofen has been reported to cause false positives on certain urine tests for marijuana. Some sources state some forms of Vit B2 can cause a false positive. However, more precise tests are available that will show that your results were false. You should demand a more specific test to verify that your results were a false positive (or stop the B complex and ibuprofen for 2-3 days and retake).