A very common side effect of Paxil is weight gain. The rates of gain are in the package labeling you should have with your prescription. As I recall the weight gain was an average of 7 pounds in about 25% of the people who took Paxil in clinical trials.
Paxil has also been associated with "carbohydrate craving"

The others Zoloft (causes severe diarreah), and Prozac (Jitters, lost sleep) aren't much better.

Wellbutrin is not chemically similar to the others, works by a better mechanism, and a better choice.

Also be wary of Celebrex. It can decrease kidney function and slow clearance of water--and make you hold on to weight. Some patients on Celebrex suffer swollen hands and feet, and other problems related to fluid retention. Finally for women, Celebrex has been shown to slow bone growth--of concern to women especially. Vioxx is the same. Worst of all is neither of these two "super aspirins" have proven better than generic naprosyn or even aspirin in the long term studies. Not worth going off your prescription plan and paying out of pocket!!