A positive Morphine test is usually due to several reasons, first of all it is possible that certain additives have been added to the food consumed, which will add some morphine based agents to the food. It is also possible to have a positive urine test for morphine if you take medication containing morphine tablets. Some of the more common of these medications are rhinitis tablets, compounded licorice tablets, cough syrup, acute syrup, and other such medications. It is possible to take these medications to cause a positive morphine test. Also some patients who use drugs can cause a positive morphine test.