My son took this for about 4 years starting at age 7. It was a HUGE help and had minimal side effects for us. Ravenous hunger and weight gain were the only side effects that were problems, though other side effects can be problems. It is a huge help with aggression and violence/anger. I hope that you can find a way to help her. I strongly recommend reading "The Explosive Child" and "Lost at School" both by Ross Greene, "What Your Explosive Child is Trying to Tell You" by Dr. Doug Riley, and ""Love adn Logic magic for Early Childhood by Fay and Cline. These will each be a help for you and for her teachers (if you can get them to use the methods).
I STRONGLY urge you to have her throoughly evaluated for sensory integration disorder by a private Occupational Therapist (OT). Schools have OTs but their evaluations only cover ways it impacts school. Sensory Integration Disorder (SID) likely is causing problems in every aspect of her life. Most kids with autistic disorders have some degree of sensory integration disorder and it can cause HUGE problems. As an adult who should have been diagnosis'd with it as a child (if anyone tested for that kind of thing back then - which they didn't), I can attest to how it messes up every single aspect of your life. Heck, my kids cannot wear scented deodorant or use scented shampoo or body wash because I get physically ill from even a whiff of them. Bright lights, loud noises, certain pitches, many many textures, etc... are all problems for me. And for my kids - though each of us has different problems related to our Sensory Integration Disorder (SID). Heck, I have a fairly limited diet because many many tastes and textures make me gag/vomit. NOT by choice, it truly is something I cannot control. Treatment for Sensory Integration Disorder (SID) is amazing, non-invasive, and can make a life-long change in your child's life. It is well worth the cost of the private Occupational Therapist (OT) evaluation, even if insurance won't pay for it. If it were my choice, I would make this one of the first things that EVERY child was evaluated for before kindergarten. Esp because the treatment is so doable and helpful and has almost no risk of side effects as long as you are properly trained (anyone can learn it, but it must be taught by an Occupational Therapist (OT) to be sure you do it properly). It makes a HUGE HUGE difference very quickly.
Hope this helps.