Now we know why nandrolone, an anabolic steroid (also known as 19-nortestosterone used in the form of esters such as nandrolone decanoate/Deca-Durabolin) causes erectile dysfunction and is often referred to as “Deca Dick.” This synthetic anabolic steroid has been available for decades. Early potential uses were for osteoporosis, anemia and muscle wasting. Anecdotal reports by bodybuilders suggest that nandrolone decreases joint pain from lifting heavy weights. Nandrolone binds to androgen receptors with greater binding affinity than testosterone, contributing to enhanced muscle growth. Nandrolone esters are among the most widely used steroids worldwide for medical use and to improve physique and performance. A new study in the Journal Steroids, March 2018, found that nandrolone combined with strenuous resistance training reduces vascular nitric oxide bioavailability and impairs endothelium-dependent vasodilation. Nandrolone can inhibit erectile function and cause sexual impairment as well as increase blood pressure and cardiovascular disease. Nandrolone plus strenuous resistance training increased reactive oxygen species (ROS, free radicals) that damage cellular tissues. It also drastically reduced vascular nitric oxide bioavailability. Nandrolone also increased arterial wall thickening and endothelial dysfunction. Nandrolone may increase the risk of cardiovascular disease and erectile dysfunction by decreasing dihydrotestosterone (DHT!), which is the active androgen involved in nitric oxide-meditated penile erections. Transdermal DHT is aging men has been shown to increase early morning erections and ability to maintain them. 5-alpha-reductase enzyme normally converts testosterone in the prostate gland and hair follicle to DHT. DHT can cause prostate enlargement and alopecia (hair loss). Treatment of benign prostatic hypertrophy and alopecia with the drug finasteride lowers DHT but has side effects such as erectile and endothelial dysfunction. I am very concerned that finasteride taken for hair loss and benign prostatic hypertrophy may cause erectile and endothelial dysfunction and increase the risk of cardiovascular disease! Many anabolic steroid users use nandrolone because it does not convert into DHT. DHT can enhance hair loss (alopecia). This is one of the reasons why men use nandrolone, or Deca, as a replacement for testosterone because it could alleviate the development of androgenic alopecia. Because nandrolone does not raise DHT, it has less effect on hair loss than exogenous testosterone (with its subsequent conversion to DHT). That’s why nandrolone may be beneficial in hypogonadal men concerned with alopecia. The downside is that while nandrolone might prevent alopecia hair loss, it may have detrimental effects on endothelial vascular and erectile function and increased potential risk of cardiovascular disease. Nandrolone use lowers levels of luteinizing hormone and testosterone through negative feedback therefore, lowering DHT formation, but DHT is required for proper nitric oxide function. By inhibiting DHT, you lower nitric oxide bioavailability and endothelial function. It is theorized that nandrolone should be administered with testosterone (“stacked”) to provide DHT and prevent erectile dysfunction. However, specific in-vivo studies examining the effects of testosterone with nandrolone in humans have not been published. Very little scientific research exists regarding the use of nandrolone and, as such— further human studies are needed.