I don't know about the effects on teens specifically, but here are some general ones:
Though anabolic steroids can cause hair loss and acne for both genders, the effects differ from females to males.
Females may face breast atrophy, increased facial and body hair growth, menstrual difficulties, an increased sex drive, and a deepened voice. Males may experience breast development, shrunken testicles, reduced sperm count, erectile dysfunction, infertility, and increased risk of prostate cancer (just a lot fun stuff, really).
Other side effects (for both genders) include heart attack or stroke, liver or kidney tumors, aggressive or manic behavior, mood swings, and hallucinations.
