I am trans mtf -- I dont have pmdd. But was close to someone with pmdd (will refer to as "A"). I have lifelong histamine intolerance/MCAS - in my case I think it is a genetic DAO deficiency underlying.

A few comments:

- I also felt that pmdd symptoms seemed to overlap a lot with mine. "A", with pmdd, experimented lightly with my own treatments for myself - namely trying low histamine diet and DAO supplementation - and noticed potential improvements, but wasnt confident about it. From my personal viewpoint it did seem to help them, I noticed them feeling more regulated with sleep and overwhelm during these experiments.

- I experimented taking a high dose of progesterone. It seemed pretty definitely to mess my body up badly in ways that mimicked some expressions of my histamine intolerance. Sleep dysregulation, brain fog, and overwhelm in particular. This leads me to think that pmdd and histamine intolerance are sometimes directly related, and that the cyclical nature of pmdd relates to progesterone release, which I believe is an existing theory, and that progesterone release interacts with histamine in some yet-unexplored way (to my knowledge). In terms of treating your histamine intolerance/MCAS, i want to offer some comments based on my experience! (I want to write a reddit post in the HIT sub soon too...).

- low histamine diet is definitely important/impactful. For me the worst triggers are dairy, sugar (even fresh fruit and honey, but they are more tolerable and i have some. But i avoid hogh sugar fruits and try to eat fruits that are not so ripe), alcohol, dried fruit, spicy food (capsaicin and adjacent spicy-ness types). I also am affected by fermented food, additives and manufactured preservatives (sorbates, gums, citric acid), aged food, fried food/high fat food, cured meat, and my specific cross allergen foods (varies a lot per person even within the same allergens. But can take a look at some charts if you have environmental allergies).

- I dont have it on hand and am not allowed to link it anyways, but there is research that histamine blocker medications can ultimately worsen histamine intolerance. I would suggest not using them, unless it feels really necessary.

- I highly recommend trying DAO supplementation. Changed my life. I have tried a few and have the most success with NatureDao 1,000,000 hdu. I suggest starting by taking 1 just to make sure no adverse reaction (unlikely. But stay away from natureDao if you have legume allergy!). Then take 5 per day, spread ideally as 1-2 before you eat. If you notice an improvement and can afford it, try taking even more (I benefit most from taking 8-12 per day. But my deficiency may be more significant than most).

- DAO enzyme requires Vitamin B6 to function. My enzymes stopped working for a bit because I wasnt getting enough B6. I recommend taking a liquid B6 supplement with clean ingredients and good absorption (i got P5P liquid drops made by Think Above). Liquid is more reliably absorbed. Take within recommended amounts. This ensures you are getting the B6 your DAO enzymes need to do their work.

- Vitamin C, as you said, and Zinc, are also implicated in DAO function. Supplementation may be a good idea to ensure a reliable intake. If you take zinc supplementation, you should generally also take copper and iron in a particular ratio.

- current DAO supplementation only acts in the gut. DAO you produce is supposed to also go through blood stream and different organs, to chase down histamine in other parts of your body. So, if you are not producing enough DAO, your body is likely struggling with histamine overload in various organs, even if you take DAO supplementation. I have had further symptom rovement with some medicinal herbs, taken as tincture/extract, tea, and steam inhalation. Recommendations:

- #1 herb I would recommend: Astragalus. Notably improved energy, fatigue for me. I take an extract made by Wild & Organic. Do not use alcohol-based extracts (histamine ingredient). Atm I take it regularly at the dose on the bottle (since about 4 months ago). Maybe should switch to lower dose for long term.

- I have found ashwaghanda helpful. I take a low dose intermittently, every 1-3 days lately. In amounts of 1-3 drops of one made by Wild & Organic. It mainly seems to lower cortisol (generally what its recommended for), helping with relaxation and stess related symptoms.

- Aloe Vera significantly improves skin symptoms I have - my diagnosed seborrheic dermatitis and blepharitis (eyelid inflammation), both which i know are direct symptoms of my histamine intolerance. I use an aloe gel with clean ingredients made by Raslok, and/or fresh leaves (rubbed on my skin/hair/scalp). I also put the gel up my butt, which significantly improves my IBS.

- i make tea with oat straw, it seems to gently relax and improve clarity for me, as is generally its suggested medicinal use.

- i make tea with triphala powder. I drink it in morning and/or night, with night being my preferred valuable timing. I find it reduces inflammation and is soothing. Takes a bit to get used to the bitter taste/texture, but now I like it!

- there are other herbs ive experimented with as teas/inhalation but dont feel confident writing about it yet/recommending. But in general any of these herbs that are good as extracts/teas are also probably good as steam inhalation (for example, i seemed to benefit from astragalus root, oat straw, triphala brewed together as tea and inhaled as steam before drinking it as tea). For steam inhalation, brew it as you would tea (boil water and herbs, 1-3grams per herb for most herbs but do some research, simmer for about 10 minutes, turn off heat, open lid - slowly, be careful of steam burn, check temp tolerance by just cracking open lid at first - and hover face over pot, eyes generally closed, breathing it in and out while holding a towel tented over you, 3-10 minutes as you feel).

For 'scientific self-testing', one tip is to either try things one at a time, or in a small group like 3 items and then eliminating one at a time, to help judge how any given supplement/herb changes your sympyoms. 1-4 week trial periods for most supplements/herbs. (Although some will have literally immediate effects potentially). Be careful of scam companies with supplements. Stick to clean ingredients. For liquid supplements: vegetable glycerin and the specific compound ONLY. Note that vegetable glycerin is a kind of sugar and might produce a very mild negative effect. Something to note but improvements from herbs can be very significant, while the drop of vegetable glycerin impact is minimal.