Hi Gilla999, I'm so sorry to hear what a horrible time you're going through. I can't add much to the replies you've had so far, but just wanted to ask you whether you feel tapering off Mirtazapine could be contributing to the resurgence in your insomnia & histamine type symptoms?
am currently slow tapering across from Mirtazapine to Trazodone - I'm down to about 2mg of Mirtazapine
I'm sure you must know this, but just in case, as well as its antidepressant effects, Mirtazapine is a potent antihistamine, which is the factor said to help with sedation when taken at low doses (at higher doses other properties such as the stimulating effects on adrenalin are said to come to the fore, sometimes even contributing to insomnia). The consensus seems to be that around 7.5mg is optimal for treating insomnia. So I'm thinking as you're down to around 2mg its effectiveness as a sedative (and) antihistamine are now probably minimal.
There is a great deal of literature on Mirtazapine & some of it seems conflicting, for instance saying the sedative effect wears off over time, but I'm not sure whether in some cases this could be related to its being titrated up to higher doses in those patients for whom it's primarily being prescribed for depression rather than insomnia, so that it becomes stimulating rather than sedative.
There are a couple of (rather unsexy - sorry) links & extracts here that refer to its antihistamine properties, but there is loads more if you want to look into it further.
https://www.psychdb.com/meds/antidepressants/nassa/mirtazapine"Why Do Lower Doses of Mirtazapine Cause More Sedation?
Mirtazapine acts mainly on 3 receptors: histaminergic, noradrenergic, and serotonergic receptors. However, at low doses (e.g. - 7.5 mg), mirtazapine has a higher affinity to (and thus preferentially blocks) the histamine-1 receptor, compared to the other 2 receptors.[2][3] At higher doses, this antihistamine activity is offset by increased noradrenergic transmission, which reduces its sedating effects."
https://smpdb.ca/view/SMP0062885"Mirtazapine is a tetracyclic H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria."
You don't say why you are tapering off Mirtazapine (I think - sorry if I've missed this) so if not because of undesirable side effects, I wonder whether staying on it for now, perhaps at the 7.5mg dose they cite as optimal for sleep is something you might want to consider, in discussion with your doctors of course.
I very much sympathise with the insomnia as this is a very longstanding problem for me & like you I had a frustrating time of it during peri trying to follow a very restrictive histamine reducing diet to little effect. RebJT is way more knowledgeable than me on HIT & I know from her posts she's also sadly suffered horribly with it. I hope you both manage to find ways of minimising these horrible symptoms during the difficult peri years & can only say try to hang on in there as things do get better with greater stability postmenopause.
Wx