The 400 range never gave me significant side effects. Once I hit 600 mg though, I started experiencing low blood pressure( only if I were to get out of bed too fast), and sometimes a hard time driving in the morning from the fatigue and dizziness, unless I slept at least 10 hours, increased appetite, and I would get twitchy, especially in my wrists. Some of the stronger side effects would go away after the morning time, such as the fatigue. I needed lots of coffee. It did help with racing thoughts to a degree.

Anything below 600 wasn't bad though. Now, I keep myself at 400 or during times I am not actively in a severe mixed or manic episode, I'll go down to 300 mg for as long as I can. We're always tweaking my Seroquel dose to keep up with my moods, but it's a good medication for me overall since I suffer from bad insomnia, and that almost always leads to a form of mania in me. I really don't like higher doses unless I'm in crisis and no other interventions are helping.