Anabolic steroids
Anabolic steroids are often taken by body-conscious men hoping to build muscle. While taking anabolic steroids, men are most likely infertile. More testosterone does not lead to higher fertility. Exactly the opposite is the case, because by taking testosterone the brain registers a higher hormone level and signals to the testicles to shut down the production of sperm cells. This brings sperm production to a standstill. Sometimes the testicles visibly shrink. Depending on the duration and preparation, male fertility can be damaged for life.