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
Actually, yes, it can. Codeine is metabolized within the body into morphine so a drug screen may come up positive for morphine. Your Dr should know this. He should know what a drugs metabolites are and that if you are prescribed codeine that you will have morphine excretion in the urine. Votes: +2.