You should warm him that steroid abuse can lead to VIOLENT AND DANGEROUS BEHAVIOUR. Steroid abuse has been associated with a wide variety of adverse effects in humans. These adverse effects include: acne, anger [popularly called 'roid rage'], development of breast in men, impotency [even in young men], blurred vision, cataracts, obesity, increased growth of body hair, high blood pressure, heart attack, liver cancer, etc. These adverse effects may emerge after many years of use.