These are very common side effects from the medication. Seroquel definitely causes me to get dry mouth, and dizziness is a big problem. In fact, out of every medication I've ever taken, I think Seroquel has caused me the worst dizziness of all (especially on high doses though or when first starting it). I no longer tolerate warm weather as well as I used to, and that could be due to the fact that it disrupts the body's ability to regulate temperature (there's heat warnings). Definitely stay hydrated and careful, especially as your body adjusts to it.