Mirtazapine sedative effects 15mg vs higher doses

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I have read a few posts on here that 15mg is more sedative than higher doses. My doctor also mentioned this to me but at the time I shrugged it off. How can this be? Surely 30 would be twice as strong as 15? Was there a study on this? Does anyone know please? Thanks

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  • Posted

    Hi Philip, put ximply the theory is that the more sedative effects of Mirtazapine are counteracted by the more activating effects you get on doses of 30mg or above.

    The sedative effects are caused by Mirtazapines anti-histaminics effects, whereas the actual anti-depressive effects of the drug are caused by it's ability to stop reabsorption of Serotonin into nerve endings in the brain.  More accurately it inhibits the sensors which monitor how much Serotonin is in synapse gaps which causes the seperate nerve endings to not re-absorb so much Serotonin.  SSRIs which Mirtazapine is not work by inhibiting the nerve endings ability to reabsorp Serotonin directly.

    Mirtazapine is also thought to have an effect on Noroadrenaline which is where my laymans knowledge ends I'm afraid.

    But essentially at 30mg and above you get more of the anti-depressive qualities of the drug which is meant to counteract the sedative effects.

    In practice I didn't find much difference between 15mg and 30mg or 45mg but then again Mirtazapine just didn't seem to work for me for whatever reason.

    Ultimately if you think the drug might be helping you and you might benefit from upping the dose try it and see how it goes.  With ADs it's often a case of balancing the benefits against the side effects.


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  • Posted

    The sedation on Mirtazipine is caused by it blocking the histamine H1 receptor.

    At 15mg the H1 is pretty much fully blocked so any higher dose will not make you more tired.

    However doses higher than 15mg do continue to increase the seretonin and (most importantly to this discussion) the Nor-epinephrine (nor-adrenaline to you and me). So with the extra adrenaline comes more alertness.

    So in a nut shell, tiredness maxes out at approx 15mg but the stimulating side continues to increase with higher doses. Thats the therory but individual variation occurs.

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  • Posted

    I was most tired at 7.5 while I was weaning. So I agree that with mirt anyhow the sedating effects work backwards. So if you need it to sleep and don't need it for depression I'd go with the lowest dose of 7.5
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  • Posted

    Hi everyone. This blogging is all new to me.  I have been on Remeron about a month or so.  I started at 15 mg and was SO groggy all day for the next few days. My doctor had me increase it to 22 mg, and then 30 mg.  I was only a bit tired upon waking at 30 mg, and it lasted only a short time.  We're are still playing with the dosage, trying to get me to sleep better, taking this drug along with another one known to help.  I just wanted to add that I had have a somewhat dry mouth no matter the dosage, and increased appetite. My doctor also had explained that the drug works "backwards" as far as feeling tired, and reading your blogs, now I really understand what she meant.  Also, now that I am back down to 15 mg, I don't notice any grogginess, so I guess you either can get use to it, or maybe just using a higher dosage several days helped me to adjust, I don't know.  I just hope my info is helpful to someone who reads this, since I was prompted to share after reading all of your helpful info.
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  • Posted

    I've been taking mirtazapine for a fair few years now, I find that it works very well for me, but I only recently found out about this sedativity difference between doses.

    Makes perfect sense when I read this chat forum smile

    What it got me wondering is...

    'does that mean that if I needed a more sedative effect due to a random night of insomnia, then I could ocassionally (not often) take a 15mg instead of a 30mg in order to help me get to sleep???'

    And would the same apply the other way round?

    'Could a person (taking 15mg) who's feeling particularly lower than they usually feel, decide to take a 30mg or 45mg for one or two nights in order to give their seriton level a quick boost?'

    I know it's probably advised against changing dose levels, but would it work and have a noticeable immediate affect in that way???

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