Just switched from Paxil to Celexa after 17 yrs. Anyone experience any significant side effects I should be aware of. Thx. I tried Pristiq but headaches and stomach pains after 6 weeks made me quit... oh also 150 mg of wellbutrin which have usedhbefore - mostly curious about Celexa 4 days so far... a bit tired but figure that's Paxil withdrawal after 17 yrs.