the only way you can test positive for marijuana is to be smoking (or ingesting) weed unless the urine test was somehow flawed or mixed up (not likely). otc cold meds will not cause a positive thc result. get another test but no one is going to buy your story that you have not be indulging in cannabis if you test positive again. you can get a blood or hair test as well as urine.
what kind of otc cold and flu medicine can cause a positive test for thc? . i took a urine test for the methadone clinic and i tested positive for marijuana. i have not smoked or have even been in contact with marijuana for over a year and a half. so what could have caused this?