Antiestrogens like aromatase inhibitors (., anastrozole ) and selective estrogen receptor modulators (., tamoxifen , raloxifene ) can interfere with and prevent the estrogenic effects of nandrolone decanoate.  5α-Reductase inhibitors like finasteride and dutasteride can prevent the inactivation of nandrolone in so-called "androgenic" tissues like the skin , hair follicles , and prostate gland and may therefore considerably increase its androgenic side effects.  This is opposite to the case of most other AAS, which are either potentiated by 5α-reductase in such tissues or are not substrates of 5α-reductase.  Antiandrogens like cyproterone acetate , spironolactone , and bicalutamide can block both the anabolic and androgenic effects of AAS like nandrolone decanoate. 
Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000.