Hi, Although Paxil is a drug that can potentially cause weight gain, not all patients really develop weight gain. in fact many times if you are really following a strict diet control, there is a much lesser likelihood of weight gain. Most of the medicines for the anxiety in this category have weight gain as a side efect in few patients. Bupropion is an alternative to consider as it has very less likelihood to cause weight gain. Celecoxib is an analgesic and is not going to help in relieving anxiety directly unless you have assocaited pain in some region of the body. It is however safe to consume it along with paxil. Also consider engaging yourself in some novel interest or activity that makes you busy to have less time to feel anxious about your current situation. Hope this helps.