The unusual properties of Deca Durabolin are due to its parent steroid, nandrolone, also known as 19-nortestosterone. One of the principal positive qualities of nandrolone is that it has relatively low conversion to estrogen compared to testosterone.
In earlier years, testosterone and nandrolone were the only pharmaceutical injectables that were both widely available to bodybuilders and economical. Estrogen control did not then exist. For this reason, Deca’s low aromatizing properties were then quite useful. Deca therefore won wide popularity.
An additional advantage of Deca Durabolin (nandrolone) is that this compound is relatively mild in terms of adverse side effects on the scalp and skin. This is because the 5-alpha reductase enzyme acts to reduce the potency of nandrolone, while in contrast many other anabolic steroids are unaffected by this enzyme, and testosterone’s potency is actually increased by it.
Further, where athletes have joint problems, in many instances use of Deca in a steroid cycle has the positive side effect of providing some aid. Even doses as low as 100 mg/week can entirely suffice for this purpose in many instances.
Unfortunately, Deca Durabolin usage very commonly has the adverse side effect of interfering with recovery of natural testosterone production after a steroid cycle. Adverse side effect on libido and/or erectile function is also common, but typically only when dosage is at least 200-400 mg/week or when the drug is used alone at any effective dose. Problems are worse when Deca is not combined with testosterone or substantial doses of more androgenic compounds such as Trenbolone Acetate, Masteron Dromostanolone Propionate, or Dianabol Methandienone. There is wide individual variability in response with regard to side effects on libido and erectile function. Depression of mood is also possible.