Mesterolone is an oral anabolic steroid, a synthetic product of the male hormone testosterone. The drug has shown value in treating men with mental health issues, such as depression, anxiety and bipolar disorders. The drug also is commonly used to treat sexual dysfunction, including low sperm count. Additionally, mesterolone may enhance the effectiveness of other steroids. Interestingly, unlike other steroids, the drug shows little value for bodybuilding, but has the same health risks involved in steroid use for that purpose.