Dex top off working way better than Vyvanse

So I’ve been on Vyvanse and recently got prescribed 10mg dex as a short-acting booster. Only been about 5 days but honestly the difference is definitely noticeable.

The dex on its own has been genuinely great. Less anxious, more functional, just feels cleaner. It only lasts 3-4 hours and I can notice the crash, but even with that it’s been a way better 5 days than I’ve had on Vyvanse alone. The Vyvanse pattern for me is basically anxiety ramping up, exhaustion right at what should be peak, then more anxiety on the comedown.

I just picked up a Vyvanse refill but now I’m wondering, is this a dosage thing? Like is the Vyvanse dose just off? Or is it something about how lisdexamfetamine metabolises vs straight dex? Because pharmacologically they should end up as the same active compound right? So I’m confused why the experience is so different.

Part of me wants to just ask my doc if I can switch to dex IR multiple times a day since that’s what’s actually working. But I’m from the US originally so I’ve been fully conditioned to expect that any conversation about preferring short-acting stimulants gets you treated like a drug seeker. Different country now but that reflex is hard to shake.

Anyone else experienced this where the IR worked noticeably better than Vyvanse? Did you end up switching, adjusting the Vyvanse dose, or what?

Cheers