I started fin at 21, have been on it 13 years this summer, no side effects. Retarded or halted my hair loss significantly, crown and vertex are intact to the naked eye, and if they are thinning it is so gradual that I have yet to notice.
This stabilization allowed me to pursue a relatively aggressive restoration gameplan for the frontal third of my scalp.
Now people think I have a full head of hair and don't know I take finasteride and have surgically restored my hairline.
I recommend finasteride without reservation, it's safe long term, especially for men in their youth.