mirtzapine to fluoxetine

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hello,i wonder if anybody can help with this, my doctor put me on 30mg of mirtazapine just over 2 weeks ago and after some initial improvement in my depression and emptyness i seemed to reach a plateau.i expected the gp to up the dosage but instead he has put me on flu.can you tell me if i still have to wait the 2/3 weeks for any beneficial effects or if i have a \"head start\" so to speak.a lot of what ive read on flu so far seems to be negative ?

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  • Posted

    Mirtazapine increases serotonergic transmission, amongst other things. Flu slows down the reuptake of serotonin and makes it available for longer – which is a good thing. They do work slightly differently in that Mirtazapine is thought to act on the 5-HT2A serotonin receptors and 5-HT3 serotonin receptors. These receptors control things like anxiety and over excitement of the central nervous system. Fluoxetine is thought to act on the 5-HT2C serotonin receptors which control other aspects of anxiety.

    Prolonged levels of stress and anxiety sometimes leads to depression due to the effects the stress hormones have on the brain over an extended period of time. So both Mirtazapine and Flu, in part at least, reduce the levels of stress hormones and allows brain chemistry to normalise over time.

    Since they both act on serotonin, it should give a head-start now that you have been moved to Fluoxetine. If you feel a little more anxious on Flu (important: and not everyone does!) initially then this is quite normal and normally goes away after a couple of weeks. Your Doctor can always prescribe a short course (a couple of weeks) of benzodiazepines if you feel you need it. Flu is not as fact acting as Mirtazapine but can be more effective for certain types of depression in the long run.

    Good luck and I hope Flu works for you as it worked for me.

    - Garch

  • Posted

    thank you for taking the time to advise me,fingers crossed
  • Posted

    just thought my update may be of some comfort to people new to flu, just over two weeks in and im definately feeling the benefits ! the 2 side affects i suffered were daily stomach upset(as if i were constantly hungry) which have thankfully gone now,and insomnia( prescribed sleeping tablets doing the trick. may i also add that this forum and reading everybodies experiences was a huge help, ta
  • Posted

    Hi bt david,

    I'm glad Flu is working for you. The stomach upsets and insomnia usually subside after a few weeks (in my experience). Flu increases the availability of the important chemical transmitter serotonin in the brain. Serotonin (or 5-HT to give its proper name) is a key chemical involved in the regulation of many body and mind functions, including mood.

    Oddy enough the stomach also uses serotonin and when you start Flu, not only does it increase the availability in the brain but also in your stomach - hence the stomach upset. After a few weeks your stomach will adjust to the new higher levels and will settle down. In fact a good side-effect of Flu and many SSRIs is that it up-regulates the efficiency of your stomach - so you better absorb nutrients.

    The insomnia normally subsides as well - as the brain adjust to the new chemical equilibrium (called homeostatus). Initially the increased availability of serotonin in the brain distrups the circadian mechanism governing the wake/sleep cycle. A bit like jet-lag. The brain has complex chemical and hormonal feedback mechanisms, some fast feedback, some slow feedback. The slow feedback mechanism responds over several weeks. So it takes the brain (and endocrine system) a good few weeks to respond to the newly enhanced levels of serotonin and return to a chemical equilibrium. When this chemical stasus is resumed, near-normal sleep patterns should return.

    Good luck ;-)


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