I was on Paxil for about a year, and I had several side effects from it. I'm prone to side effects from meds anyway, so my Dr. started me on 1/4 of the lowest dose for 2 weeks, then moved to 1/2 dose for 2 weeks, then finally to the full "lowest dose" for a month. After that we gradually upped it again until we hit a level where there was a noticable improvement. I had to do the same thing in reverse to get off of it because I had bad side effects from the withdrawal, too.
Some of the side effects I had were dizziness, nausea, mild headaches, and while I was on Paxil I gained about 30 lbs in 10 months. It took about 18 months of being off the Paxil before my metabolism was back on track and then most of the weight came off quickly. The dizziness was sometimes very bad, but I found that it faded about 3 or 4 days into each stage of ramping up the dosage.
Any anti-depressant or anti-anxiety drug will take a little while to work, so it's really important to be patient with yourself in the process.

It took about 3 months for me before I really felt "like my old self" again, but there was a gradual improvement starting at the end of the first month.
I'm glad I don't need the Paxil anymore, but I'd go back on it again if I ever needed to. It really helped me during a rough season in my life, and helped me to enjoy life again. Blessings to you on this journey, and I hope you will experience a minimum of side effects and will enjoy your trip to WDW!
