I literally spent about 2 hours looking for a good solid answer and im sure many many people are asking the same question. Will Benzedrex show up on a drug test as methamphetamine? And many of you may be thinking that propylhexedrine (hexahydro"methamphetamine") isnt technically an amphetamine. Which is exactly what I kept telling myself. I could sit here all day and be scientific but I came here for one reason and thats to warn you that YOU WILL FAIL a drug test for METHamphetamine. As for it being a false positive, im not to sure but the test definately thinks I bathed in a pool of meth. https://m.flickr.com/#/photos/ [email protected] /14380428517/ Just make sure you always keep in mind that this stuff will cause a positive and to never even think about doing it if you know you have a drug test coming up via probation, job ir whatever. In conclusion benzedrex isnt as foolproof as we all thought, it can bite you in the *** as quick as you can get the cotton out. I hope this helps clear some peoples mind as it did mine.