From the Research
A morphine-to-codeine ratio of less than 2 does not reliably distinguish between codeine use and poppy seed ingestion, as both scenarios can produce low morphine-codeine ratios. When codeine is taken, it metabolizes partially to morphine in the body, typically resulting in a morphine-codeine ratio below 1 1. Similarly, poppy seeds contain varying amounts of both compounds, often with higher codeine than morphine content, which can also produce ratios below 2. The ratio alone is insufficient for definitive determination of the source.
Additional factors that complicate interpretation include individual metabolic differences, timing of the test relative to ingestion, quantity consumed, and processing methods for poppy seeds. More comprehensive testing approaches, including detection of other metabolites, consideration of concentration levels, and clinical history, are necessary for accurate determination of whether a positive test resulted from medication use or dietary sources 1.
Some studies have suggested that codeine concentrations exceeding 300 ng/mL coupled with morphine-to-codeine ratios <2 are indicative of codeine consumption and, therefore, exclude poppy seed consumption as a legitimate explanation for the test result 1. However, a recent study found that consumption of poppy seed-containing food products can result in opiate-positive urine drug test results and may pose challenges in distinguishing poppy seed consumption from opiate administration, even with these guidelines 1.
In real-life clinical practice, it is essential to consider the clinical history and other factors when interpreting test results, rather than relying solely on the morphine-to-codeine ratio. A comprehensive approach, including detection of other metabolites and consideration of concentration levels, is necessary to accurately determine the source of a positive test result. This approach can help minimize the risk of misinterpretation and ensure that patients receive appropriate care and treatment.