I have over 7 years of experience with Seroquel. I can share with you how it worked (or didn't) for me.
The first time I took Seroquel I was completely loopy. I had trouble walking from the bathroom to my bed. I fell into bed and slept like a rock. That was somewhere around 200mg.
After the first 3 nights, the "falling down drunk" feeling was gone. But whatever S. was supposed to do, it didn't. The pdocs I had kept insisting that I stay on the stuff, which I did. In 5 years I gained over 100lbs. I felt that if my stomach was empty I was starving and felt unwell...nauseated and weak.
After 5 years my pdoc reluctantly agreed to drop the dose. By that time I had high blood pressure, high cholesterol, high glucose.
I went down in dose - still insisting that the Seroquel wasn't doing anything except make me insanely hungry, especially for sugary foods. Normally, I'm a cautious and healthy eater, so the hunger thing was upsetting - to say the least.
At long last, 6 years into taking S. I flatly refused to stay on the higher dose. My pdoc dropped the amount down to 50mg, then 25, then 12.5. At that dose the purpose was to have good sleep. It worked for that.
Eventually, at about the 7 year mark, I completely stopped taking it. And could not sleep for more than 2 hours at a time (after trying to fall asleep for an hour or more).
So. Here I am, back on 25mg every night. Sometimes the 25mg helps me sleep, other times, not at all.
I am not pleased about being on it and wish I would have been proactive in the beginning, told the first pdoc who prescribed it "NO."
I always took Seroquel at night. I was on ER for a short time and found it weird. I don't exactly remember why, but I know I had it changed back to regular.
So, to summarize. For me, Seroquel didn't do anything except cause me to gain a lot of weight and develop health problems. At the very low dose, 25mg or less, it sometimes helps me sleep.
Many people find Seroquel to be extremely helpful. I am not one of those people.
As far as dry mouth, dry eyes- in my experience all AP's cause that, at least intermittently.
I am currently taking an AP, Trilafon, that dramatically lessens my severe anxiety and doesn't seem to have an excess of side effects.