Testosterone has been subject to abuse, typically at doses higher than recommended for approved indication and in combination with other anabolic androgenic steroids; anabolic androgenic steroid abuse can lead to serious cardiovascular and psychiatric adverse reactions; if testosterone abuse suspected, check serum testosterone concentrations to ensure they are within therapeutic range; consider possibility of testosterone and anabolic androgenic steroid abuse in suspected patients who present with serious cardiovascular or psychiatric adverse events
Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males.