Vyvanse--side effects and too much? | ADHD Information

So I was put on Vyvanse, two side effects are scaring me, and I'm on the
lowest dose that gives me any positive effect. Overall though, it's my
favorite so far. The peak and crash of Adderall made me feel too "drugged
out" and ritalin just doesn't do it for me.

Anyway, today, I bit all 10 of my nails down to stubs, most of them to the
point that the bled. My fingers hurt really badly now, but if I don't have
something to chew on, I still continue to bite them unconsciously and I
can't seem to stop myself.

Every time I eat I feel like I'm force feeding myself. It's getting a little
better, but there were days where I could only manage a cracker.

I'm wondering if I'm taking too much, but my doctor said the only side
effect i should really worry about is about the inability to differentiate
between the occasional increased heartbeat caused by the vyvanse and
the onset of a panic attack. And so far I can tell the two apart just fine.

I think the most shocking thing to me is biting my nails down until I bled.
My eating habits go through cycles, but I've never just kept gnawing away
after I was bleeding. Gum stops the biting though, so is this just a side
effect I'm going to have to live with, or am I maybe too high a dose
(maybe Vyvanse just isn't for me)

Also, not sure if it's relevant, but I'm 18, 5 ft 5, about 125 lbs, and other
medications I'm on are: Cymbalta, xanax, klonopin, and birth control.