Despite being 'performance enhancing', the negatives of anabolic steroids outweighs the positives about it significantly. Steroids can damage the linings of your smooth muscles and the loose connective tissues, like the reticular and cuboidal cells in your kidneys/liver (both are responsible for filtration) because of the sudden increase in levels of testosterone. Anabolic steroids can also cause problems with your cardiac muscle tissues and the intercalated discs that help control the contractions of your ventricles in your heart, specifically the left ventricle, which has the deoxygenated blood. Anabolic steroids also negatively effect the growth of your bones and can cause dependency, leading to secondary sex characteristics of the opposite sex: enlarged breasts, atrophy of the penis, baldness, etc. Also, anabolic steroids increase cholesterol levels (steroids are fats , and excess fats turn areolar connective tissue, due to mesenchymal cells, into adipose tissues which contains a lot of energy and is hard to burn).
Anatomy and physiology... Basic biology.