There have been many reports of vyvanse causing acne. Maybe she can switch meds to see if that is really the cause. It is worth a try because accutane has its own side effects and especially for girls who may be sexually active...I'm not saying that your daughter is though...but getting pregnant while on accutane is very bad.
Spironolactone. Girls can take it, not boys. That is the key to cystic acne for girls. All hormonal based. I'm 49 and have had them since 17 years old. Still get them, but only once a year. Taking Solodyn 105 mg. with it, too. That's a high dose, but necessary (weigh 135lbs). Spironolactone comes in 25mg pills. One pill a day is not enough! That won't fix anything. I take 100 mg a day to maintain. 50 mg in the morning and 50mg at night. I take more if I need to just to cut the feeding to the androgen glands that produce too much oils that cause the cysts. No fancy face washes. Only Aveeno Daily Complexion face pads. Once in the morning and once at night with the wipes. That's it. My cystic acne was so bad I would get cortisone shots in them to shrink them. Over time that didn't do the trick and I was left with only scars. Found a doctor who finally knew what he was doing. Prescribed the spironolactone (water pill). It is unreal the results.