 [ Symptoms ] can ondansetron show up positive for thc on a drug test  i was recently dropped from my doctor after 16 years of being a model patient in april i took a drug test and was terminated because he said my test was bad that is all the explanation i got i do not do any drugs i am not prescribed but i was given zofran ondansetron for nausea i only take it a couple times a month can this prescription in anyway make you have a bad drug test if not and he will not tell me specifically what was wrong with my drug test what can i do so this does not happen again [ Disease ] i found a little information about this online subj zofran date <negative_smiley>242010 we have a patient who is taking zofran and came up positive on a drug test for syboxone do you know of any reason why someone taking zofran would test positive for syboxone tim askdocweb we were unable to discover any reason for zofran to cause a false positive on a urine drug screen zofran ondansetron is used to prevent nausea and vomiting caused by cancer chemotherapy radiation therapy and surgery zofran is in a class of medications called 5 ht3 receptor antagonists it works by blocking the action of serotonin a natural substance that may cause nausea and vomiting so to me that means there might have been something else causing the false positive could you have eaten poppy seeds for example also he should not have kicked you out of his practice without a confirmation test because those screenings are known to have a certain error rate either call his boss and complain or get yourself a new doctor who will actually give the chance to clear yourself