Commonly Prescribed Medications and Potential False-positive Urine Drug Screens. Nancy C. Brahm; Lynn L. Yeager; Mark D. Fox; Kevin C. Farmer; Tony A. Palmer Published online..Medications & substances causing false positives according to a report by the los angeles times new service, a study of 161 prescription and over. Siemens Rail Automation Siemens Rail Automation purchases additional Kinesix software for their work in train control management. This does not mean these medications, prescriptions or foods will always cause a false drug test. The actual false drug screening can not be anticipated nor should. Is Dextromethorphan a Concern for Causing a False Positive during Urine Drug Screening? Michael F. Neerman, PhD, FACB; Chinemerem L. Uzoegwu, BSN, RN YES It can on the simple tests they do on the spot. When sent to a lab it should show it was a false positive though. I looked it up and Claratin-D has Loratadine in. Find patient medical information for Guaifenesin AC oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. Promethazine-DM is the generic form of Phenergan-DM. It is a prescription medication available in syrup form that contains promethazine and dextromethorphan. False positive for methamphetamine on drug tests of people using ephedra. Can taking ephedra (also called ma huang) cause a "false positive" for. I am a methadone maintenance patient & have to drug test once a month. While reading the other comments I saw it came back false positive for Methadone but that won.