My daughter is also 11 and also having some bad issues with acne but I'd never even consider Accutane. It was taken off the market in 2009 in the United States so I'm not sure it would even be an option. But it has too many questionable properties anyway. These are from Wikipedia:
"The U.S. Food and Drug Administration's (FDA) medication guide for Accutane states the drug 'may stop long bone growth in teenagers who are still growing.'"
"Various case reports of depression, suicidal ideation, suicide attempt, and suicide in patients treated with isotretinoin have been reported to the U.S. FDA Adverse Events Reporting System, with 431 cases reported between 1982 and May 2001 – of these, 37 patients had committed suicide." (And those are only the cases that made it into the official reporting system--there is plenty of anecdotal evidence of Accutane's link to depression especially in teenagers.)
And you've heard from others about its possible link to inflammatory bowel disease.
Sure, she might not have any of these side effects. But there's just as good a chance that she could have them. It's not worth risking her health or even her life to clear up her skin. Why not try over the counter products first and at the same time help her adjust to the idea that hormones are not something to be "cured" but something that has to be ridden out with the best possible help? That would not include this very dodgy drug.
We are currently using Neutrogena's scrub that contains salicylic acid for acne, followed by Neutrogena's matching toner with salicylic acid, and when needed, the same company's gel medicine for applying directly to pimples -- also with salicylic acid. I would not mix different over the counter medications such as salicylic acid and benzoyl peroxide -- try one or the other at a time to see what works best for her. It will take time and both she and you will have to be patient for these things to work. The Neutrogena products so far work pretty well IF used regularly, twice a day, and religiously. My daughter still has generally bumpy forehead skin but the bumps are not showing as much and not erupting as pimples as much, again, IF she uses the products consistently. You can't fight hormones, you can only work around them.