DP isn't autistic but she does have severe anxiety and panic disorder so I figured I'd reply!
She's tried citalopram and it was horrendous - she ended up pratically convulsing with it and had to come off it, prozac didn't do anything for her neither did most of the other meds she tried (at last count it was 10).
She's currently on atenolol (beta blocker), haloperidol and lofepramine (a combination that works well for her paranoia, depression and anxiety) but it's taken over 5 years and many, many different combinations to find what works for her.
Off meds she's a mess, on meds she can just about cope through the day. Having seen the difference medication makes to her I'd strongly recommend trying your daughter on whatever is suggested for her -yes, there may well be side effects (DP feels faint a lot, feels itchy all the time - she takes antihistamines for that - and sweating) but the benefits are well worth it.