Cold sores are caused by the herpes simplex type 1 virus and are contagious whereas canker sores are not. Also, cold sores can appear outside the mouth in places such as under the nose, on the lips or under the chin while canker sores always appear inside the mouth.anker sores, or aphthous stomatitis, are small ulcers in your mouth that cause pain and discomfort when talking or eating. Canker sores come in two varieties: simple and complex.
Codeine, which is found in many pain relievers, may cause a false positive for morphine or heroin because of its similar chemical structure. Antibiotics. Certain newly developed antibiotics including amoxicillin and ampicillin have been reported to cause false positives for cocaine. DHEA
What legal medications cause a false positive for opiates during drug testing? I work at a lab that is certified to do drug testing. Occasionally we do what we call rapidtox test (on-site) where I just put simple drops of urine onto the test and wait to read results in a few minutes (just like a pregnancy test). Twice in the past week I've had two different patients come out positive for...