only if testing for steroids
I can't say for sure what it would do, but I highly doubt you'll test positive for marijuana or cocaine. Dutasteride looks very similar to testosterone, and the are many steroids that can be tested for in one test, and they all look like testosterone. Do a google image search if you want. Dutasteride also increases testosterone levels, though degreasing DHT levels, so those at least cancel. I don't know what the ratio of testosterone in your body is compared to Dutasteride. If one enzyme makes many conversions, I'd think you have less dutasteride than test, but maybe we intake a lot of dutasteride to compete with test with sheer numbers. Most steroid users (if that is what you are affraid of failing) take a lot of steroids, up to 100 times the amount of testosterone in their bodies. I think dutasteride would at most appear as double the count. Just call the nurse, unless they will say it is illegal for you to have imported it.