Hi, Becky -

It is often hard to understand when a new doctor changes prescriptions that are working well. I think you should question him/her closely about the reason for the shift - you have a right to know why and to have full information about each drug, its interactions with others and its potential side effects. Celexa and Prozac are similar in their action of targeting serotonin - they're both SSRIs (selective serotonin reuptake inhibitors). Effexor works on both serotonin and norepinephrine - as Cymbalta also does. Both are SNRIs (serotonin norepinephrine reuptake inhibitors). One possible reason for the shift that I can think of is a concern that combining two drugs that increase the amount of serotonin in your system could push the level of this neurotransmitter too high, leading to serotonin syndrome or toxicity, which is quite serious.

If you do stop effexor, you need to be very careful to do it gradually - and keep watching for any ill effects. If you stop suddenly, you can very likely have any of a long list of reported withdrawal symptoms - dizziness, headache, nausea, electric shock-like sensations, sweating, confusion, nightmares and vertigo. Some people get these symptoms if they miss even one dose.

Taking prozac while you're withdrawing from effexor lessens the danger of these reactions since it prevents a sudden drop in the level of serotonin.

John