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Today I want to talk about an important aspect of #MCAS treatment: how do you know if you are taking Too Many Antihistamines

(Note: this is not a substitute for medical advice from your doctor, please talk to them before changing your meds)
Specifically, I want to talk about anticholinergic toxicity.

First off, I have to talk about the autonomic nervous system.
So the autonomic nervous system has two parts: the sympathetic nervous system (think fight or flight) and the parasympathetic nervous system (the part that theoretically calms you tf down after fight or flight is activated).
There are meds which affect the autonomic nervous system: anticholinergics and cholinergics.

Anticholinergics enhance the sympathetic (fight/flight) response.

Cholinergics enhance the parasympathetic response.

(I know this seems backwards to me too but I double checked)
So a lot of meds have anticholinergic effects, including most antihistamines and many antidepressants.

When I asked my doctors which of my meds were anticholinergic, they actually weren't sure about meds outside their specialty. So I had to talk to my pharmacist.
Anyway I have not found A Complete List of Anticholinergics, so if you want to find out exactly how many you are on, I would suggest talking to your doctor (s) and or pharmacist.
The thing is, when you take multiple anticholinergics they can end up being Too Effective, and you can end up with anticholinergic toxicity which is a medical emergency

It's important especially for folks with MCAS to know the signs, since we can be on high dose antihistamines
If you can read a lot of medical jargon, this is a really good overview of Anticholinergic Toxicity…
[ableist language]

So the kinda ableist mnemonic for anticholinergic toxicity is as follows:

"Mad as a hatter" = altered mental state

"Blind as a bat" = dilated pupils

"Red as a beat" = flushed skin

"Hot as a hare" = dry skin

"Dry as a bone" = dry mucous membranes Infographic of mnemonic described in tweet
"but wait" you are probably saying "flushed skin and altered mental state can both be symptoms of MCAS, so how can I tell if they're actually a symptom of anticholinergic toxicity??"

(Also, full disclosure, some dryness is a side effect of antihistamines. Love bodies 🤦)
Here is where I say, if you are concerned about this, I would definitely bring it up with your doctor and talk about how many anticholinergics you're on, what warning signs to look out for vs what is your baseline, etc

I'm also going to offer a Cautionary Tale
So in 2016, before I knew MCAS even existed, I was trying to research what tf was going on with my body, and I found out about anticholinergic toxicity. I was struggling with communication with medical providers, so I uh...did an experiment
I found out which of my meds were anticholinergics and one by one I titrated myself off of them

(Note: this was also motivated by anxiety about the election and Rs cutting my healthcare, so I also just wanted to see if I could physically survive without meds)

do NOT recommend
I mean, the upside was that I found out Lyrica was not helping my pain, so I eventually switched to a different med. (Meloxicam, which ironically made my as yet undiagnosed MCAS worse, and then eventually low dose naltrexone, which is really helping.)

Again, do NOT recommend
But also without anticholinergics, again the primary type of med used to treat MCAS, my MCAS got A Lot Worse and again I didn't know what was happening so I went back on my meds but my baseline was way worse for a couple years.

Again, do NOT recommend.
So these days I mostly just try to keep an eye on what my baseline actually is, and if that changes drastically (especially if I'm confused, have dilated pupils, flushed, and have dry skin and mucous membranes) then I get in touch with my doctor

Especially if I'm increasing meds
Anyway, this is just something I think the #MCAS community needs to be aware of as we often end up on multiple anticholinergics or higher doses of them, and I haven't seen it discussed very often
Again, if you're concerned, talk to your doctor. Maybe you can (together) figure out which meds are most effective and if there are ways to safely reduce certain medications. Maybe if you reduce exposure to triggers, you won't need as many meds.
The SECOND aspect of Possibly Taking Too Many Meds for MCAS that I want to talk about is Benadryl and potential rebound reactions

It's covered in this post from MastAttack:…
Basically, Benadryl is a very strong and fast acting antihistamine. It binds to histamine in your bloodstream. When it wears off (in ~6 hours), the histamine is still in your bloodstream and free to wreak havoc again.
So you can react *to the Benadryl wearing off*, but it can feel just like a new reaction.

If you take more Benadryl, you can end up basically stuck in a reaction cycle

(Kind of like how Too Many Migraine Meds can give you a headache)
Additionally, if you take Benadryl every day or for every flare, it may not work as well for severe reactions when you really need it.

I'm not saying "never take Benadryl", you just might want to check with your doctor about when to take it so it's most effective.
Finally, I realize I've said "talk to your doctor" about a zillion times in this thread, but *finding* a doctor who knows about MCAS is not easy

There's insurance issues, if doctors in your country/state even treat MCAS, etc.
If you're still trying to find a doctor to test for / manage MCAS, here are my best recommendations:

1. Find a local patient group for MCAS or comorbidities (EDS, POTS) and ask around.

2. Check the Mastocytosis Society physician database:…
3. Email Dr Afrin and ask if he has recommendations in your area. (I emailed him a question about one of his papers, and he got back to me the same day.)…
4. If you have a doctor who you have a good working relationship with, see if they are willing to learn more about MCAS via, for example, reading Dr Afrin's book or The Provider Primer Series on MastAttack (it comes with citations 😍)…
5. If you are already seeing a doctor who specializes in EDS or POTS, they are likely to know something about MCAS and also likely to know who treats it in your area. (I don't recommend starting here if you're primarily worried about MCAS, their waiting lists are LONG)
Finally, here is a thread about my ongoing experience with diagnosis for MCAS (I currently have a preliminary diagnosis based on symptoms and response to treatment)

I uh probably should have linked this at the top of the thread, here is a 101 on MCAS

Here is a thread I did about criteria I use when I'm trying to find a doctor. (But also sometimes realistically it's just "are they taking new patients and on my insurance plan")

If you would like to help me in my ongoing Odyssey with chronic illness, here's a link to my Amazon wish list

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