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. 
Around fifth part of the injected steroid binds to progestin receptors (due to the absence of a carbon atom in the 19 position), and therefore, such reactions as the suppression of secretion of gonadotropin-releasing hormone, increased production of prolactin, a significant decrease in libido should not be excluded. Weak erection - the most pronounced and severe consequence of abuse of deca nandrolone. Exceeding of the recommended dosage and duration of the course may cause rhinitis, headache, back pain, rash. In general, the side effects of nortestosterone decanoate - rather the exception than the rule.
NPP is a nandrolone ester , or a prodrug of nandrolone .   As such, it is an androgen and anabolic steroid , or an agonist of the androgen receptor , the biological target of androgens like testosterone .   Relative to testosterone, NPP has enhanced anabolic effects and reduced androgenic effects.   In addition to its anabolic and androgenic activity, NPP has low estrogenic activity (via its metabolite estradiol ) and moderate progestogenic activity.  Like other AAS, NPP has antigonadotropic effects, which are due to both its androgenic and progestogenic activity.