Can Propecia Interfere with My 18 Year Old Son’s Genitalia Growth?

I’d like to know if finasteride is safe for an 18 year old boy. Can it interfere with a possible genitalia growth spurt that I’ve been told can occur even after complete bone growth up to age 20 or 21? My son appears to have male pattern baldness, so his Dermatologist has put him on the drug, but his Endocrinologist advises against it. My son doesn’t want to lose his hair so he’s taking Propecia, but doesn’t know about the other possible problem. It’s not something I want him worrying about unless the drug can really interfere with genitalia growth, in which case he should know so he can decide for himself whether or not to take the drug. Please advise.

Propecia (finasteride 1mg) is safe for 18 year olds and this medication is not known to retard genitalia development in young men. The 5-year effectiveness and safety study submitted to the FDA included men aged 18 to 41 years old. He is correct that to hold on to his hair, this is the best approach.