I was on accutane when I was 19 (8 yrs ago), and though I'm not up to date on the current thinking about it I can tell you my experience with it.
First of all, as far as clearing up acne it sure does work. I had suffered with terrible (cystic) acne from age 14. It was extremely difficult emotionally to be going through my teen years and always feeling so self consious about my complexion. I had been on every acne medication available and nothing had worked. I knew the bad effects accutane could have, but for me I was desparate and was willing to take the side effects if it would clear up my face. I now hear of kids going on accutane for mild cases of acne and I think this is extremely irresponsible of the parents and doctors. But for a severe case where nothing else has worked, it can be a god send.
As far as side effects I suffered, I would not wish them on anyone. It dried up my nose to the point of daily nosebleeds from the cracking skin in there, my lips were always dry and cracked, and my hair started falling out in clumps. That along with the required monthly blood tests made the drug no fun at all. Now I know that there are many more serious side effects that are possible and I am thankful that I did not experience any of those.
And after all that, after a couple years of clear skin, the acne returned. Though not as severe, it was again cystic and I was miserable. By that time I knew I did not want to go the drug route again, so I bought a product I saw on an infomercial called pro-active. I was very skeptical, but I tried it and it really cleared up my skin as long as I used it as directed. The moment I slacked off, the I would start getting break outs again. I used that for a couple years and then stopped b/c I felt I no longer needed it. Now I just wash my face with a mild cleanser and only suffer from occasional break outs, but nothing I would call "acne."
Looking back, I truely believe that if I had changed my diet and became more healthy overall, my skin condition would have improved without all the drugs. I lived on a horrible diet of junk food and hardly any fresh whole foods. Of course with that diet my body was bound to have problems and for me it manifested in the skin.
As far as your step daughter goes...I would recommend trying to encourage her to try the pro-active. It is a topical treatment that is very gentle and really works. But if her acne is severe, like mine was, she is probably just so desparate to get rid of it that she is willing to take the risk of accutane. Please try to educate her if you can.
Carmen