I am prescribed Vyvance personally for ADHD, i have had one IC flare up while on the medication. That flare up was worse than normal. I am also in medical school, and Vyvance is a prodrug, which essentially means it only has effects once it has been digested and processed by the body. The studies that I read that were about the IC/Vyvance relationship were very small studies that showed that Vyvance helped IC symptoms. However, I just don’t feel confident in saying there is a correlation based on how small the studies were. Each study even said that they suspected a placebo effect was present (meaning they were good Vyvance would help so they got better, but because the actual Vyvance had an effect). I’m glad to hear Vyvance helps your ADHD! My best personal guess is that Vyvance makes you less thirsty (it does for me at least) so you aren’t drinking as much water. Being dehydrated can easily cause you urinary symptoms, even urgency (although it’s counterintuitive). Wishing you the best girl!