I was surprised by the number of side effects I had initially. They seem to have gotten better, but I'm only on day 4 of taking them (Vyvanse).

First day I knew when they kicked in. It was like suddenly wearing blinders for a horse. Everything was in focus.

Then I had heart palpitations, would randomly feel jittery, hot and cold flashes, and had ED symptoms. Now that I'm on my 4th day, I think I've gotten used to the drug because all of the symptoms except feeling cold the last few hours before it wears off are pretty much gone.

I sort of expected to be more focused than I am on the drug and it would be something like the stereotypical ADHD "dead emotions and hyper focus" but it's just a subtle "ability to do things without distraction a bit easier".