Hi and welcome to Healthcare Magic. Thanks for your question...
Prozac (
Fluoxetine) is an anti-depressant belonging to a class called 'SSRIs'.
Cymbalta (
Duloxetine) is also an anti-depressant belonging to a different class called 'SNRIs'. In addition to being used for depressive and
anxiety disorders, Duloxetine (Cymbalta) is also used for the treatment of neuropathy and certain central pain syndromes such as
fibromyalgia.
Now, any anti-depressant which has been continuously taken for a long period of time should not be stopped abruptly as it may cause 'discontinuation symptoms'. However, if any medication has caused serious side effects, then the first step would be to stop that medication (...and you have mentioned that Cymbalta has caused you significant side effects).
The other important thing to note is that though Prozac and Cymbalta belong to different classes, their pharmacological effects are similar i.e. both medication have an effect of increasing the levels of a neuro-chemical called 'serotonin' in the brain. So, taking two medicines which have a similar pharmacological effect can compound the effect and this can sometimes cause dangerously high levels of serotonin (resulting in what is called a "serotonin syndrome") This must have been the reason why your doctor has told you not to not to take Prozac till the Cymbalta is 'cleared out' of your system. The elimination 'half-life' of Cymbalta is about 12 hours.
Please discuss with your doctor about the further management plan and when he is planning to restart you on Prozac.
All the best.
-Dr. Jonas Sundarakumar
Consultant Psychiatrist