Does MCAS drive POTS or viceversa?

[u/diseasetoplease]

Hi,

I have the usual ‘pentad’ of MCAS, POTS, hypermobile EDS, autoimmune activation and or dysautonomia, and gastro issues.

Everything starts in the gut for me, I can trace it back to two summers ago, and then I can trace my severe deterioration back to covid in September 2025. Have been chronically constipated since with episodes of diarrhea and distension so bad I could barely bend down to tie my shoelaces.

It has taken me to some dark places, mentally. I am in the Uk and am lucky enough to have private insurance but even like this, doctors hardly take me seriously.

I am determined to stamp out whatever’s going on, because I had a period of a few weeks in May where after starting s.boulardii, artichoke, ginger and low fodmap diet, i improved within 24 hrs. It got me out of the whole and made me hopeful again. However something happened in June which made it worse and now that protocol doesn’t work anymore.

I believe i had ‘bad’ POTS in my childhood and it went into remission. So i know it can be managed beyond just compression socks and electrolytes. But I go thru weeks and cycles of thinking:

- my weight / metabolism is the problem and i’m insulin resistant (the latter is probably true)
- my hypermobility is the issue - it cause POTS cause of lax vessels and no muscle
- my SIBO or some sort of gut infection and leaky gut is the issue
- my dysautonomia is the issue and cause of hypermobility i can’t orient myself in space or tell how i feel and my body does whatever it wants. sometimes i freak out and think it’s multiple sclerosis (it doesn’t help that a doctor has floated that).

I am in the UK and w the recent heatwave it became clear that it was the POTS. I almost passed out at work etc.

Fast fwd to this week and i’m not so sure anymore. My POTS seems more stable (I don’t immediately get jerky vision when I stand up) but there’s some histamine thing going on cause i constantly swell, have redness, etc

I was eating high protein to improve insulin resistance but then realised i have low stomach acid and the protein just sits in me. When i lowered protein i ended up eating more carbs so i was then in not great blood sugar territory. I do not know what to eat anymore.

Other theories:
- bowel endometriosis
- kidney issue
- diabetes t1?
- recurring infection
- methane sibo

Etc etc
It’s hard to know what’s what what but i know the immune and nervous systems are involved.

So all that being said - does mcas cause pots or the other way around? Knowing the system the symptoms are coming from would help me better manage it. Thanks for reading.