This implies that you have more than a specific amount of it in your body. If the test you took has a cutoff below the amount of opium in poppy seeds, you may produce a positive result. Since the morphine present in poppy seeds generates positive results, it will not appear as methadone on the test. Doxylamine, found in Unisom and other over-the-counter sleep aids, may also cause a false positive on drug tests for methadone

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