I'm going to add to 'most common side effects', interdose SSRI withdrawal.. Paxil's really fallen out of favor because it's got a short duration of action and one of the worst abrupt discontinuation syndromes for SSRIs in the book.

I did withdraw from 80 of it once after it stopped working, and I felt like I was falling down an elevator shaft every second of being awake while being electrocuted through my eyeballs and sweating like Evander Holyfield in round 4.

It -WAS- a really, really effective medication, but it kept losing potency and I ended up way above the MFR max dose (this was in the 90's right when it came out).. and it still just stopped working.