Histamine Intolerance / MCAS

Histamine Intolerance (HI)/ Mast Cell Activation Syndrome (MCAS)

Histamine intolerance and MCAS are not the same thing. A person can have one of these, or both of these. Here’s a helpful article if you’re trying to differentiate which one you may have.

Dealing with MCAS symptoms, which began a few months after my excision surgery, has been extremely difficult. Not to mention, shocking! I had no idea a person could react – and so severely – to countless foods, products, lifestyle habits, and activities. Unfortunately, this resulted in me having to overhaul my entire life (again, after having once done that for endometriosis), which was devastating and overwhelming, especially since I was only 6 months post-op when the symptoms began and was still healing both physically and emotionally from excision. The grief and fear I felt at the onset of this condition was immense. It felt completely hopeless, but 2 years later, I’ve managed to lessen my reactions and even bring back pieces of my life that I had to cut out. Not everything, but enough that I don’t feel anymore like my life was reduced to the bare bones.

Getting diagnosed

Many allergists are not familiar with MCAS, and/or have never heard of histamine intolerance. It’s important to see an allergist who is knowledgeable in MCAS if you suspect you have it. “Key steps in diagnosis MCAS include recognising clinical symptoms, investigating response to treatment, undertaking mediator tests and ruling out other diagnoses.” Source: Mast Cell Action). These can include things like testing your histamine, tryptase, and other mediators, as well as putting you on a trial of H1/H2 histamine blockers for 2 weeks to see if your symptoms improve.

However, there can be issues with the tests. For example, histamine in urine can break down quickly, and if it’s not stored correctly it can mess up the results. Many doctors use tryptase as the marker for the disease, but not everyone has high tryptase levels as mast cells can release hundreds of mediators! My doctor is very focused on my normal levels of tryptase, and thinks I have “dysautonomia with a mast cell component”, even though I tick all the boxes for MCAS between my histamine response, my multi-system symptoms that I have within minutes of exposure to a trigger, and the fact that I have more MCAS triggers than I can count. I personally think that I have MCAS.

Therefore, since my doctor and I both agree that my mast cells are somehow playing a role in my current problems, I’ve been working from that suspected diagnosis and focusing on ways to live better with this condition.

Contributing factors to MCAS

Everyone has different contributing factors to MCAS. Here’s the ones I’ve discovered in myself. (Remember, these are personal to me, but I list them here to show that addressing MCAS may need a multidisciplinary approach.) I worked with a naturopath for some of these, and while I had a really helpful experience, this doesn’t negate that there’s a lot of non-evidenced based testing and science among this type of medicine. If you’re thinking about working with a functional medicine doctor or naturopath, see my page here.


After losing an ovary, my hormones and menstrual cycle changed. I began having perimenopause symptoms 6 months later at 34. I also learned through hormone testing and a gene analysis that my body seems to have trouble with phase 2 of estrogen detoxification. I’ve been taking oral progesterone for a few years now and it’s really helping. I also took supplements for 6 months (recommended by my naturopath) to support my hormone health and estrogen detoxification.

SIBO and gut dysbiosis

I did a comprehensive stool sample which showed gut dysbiosis as well as pathogens like giardia. I took 2 months of herbal anti-microbials for this; in doing so, my MCAS symptoms of anaphylaxis and racing heart disappeared! My naturopath then suspected I had SIBO due to my clinical symptoms, and we continued with a few rounds of different herbal anti-microbials for that.

Stress, trauma, being in fight-or-flight, not having safety in my body

Those are various names/descriptors for what I consider to really all fall under the same umbrella of being in an upregulated state with my autonomic nervous system: being in “fight or flight” without me even being aware that I’m in that state of activation. I’ve been using the Curable app to find safety in my body, to learn how to truly relax, and how even tendencies like self-criticism and perfectionism can put our bodies into an activated state of “danger”.

Food triggers like histamine and others

Going on a low histamine diet has done wonders. At first, I was ultra-low histamine because I had immediate, serious reactions whenever I ate food, even foods that are low histamine. My diet was very limited for several months, which definitely affected my mental health. Especially because the food I love like fish, tomatoes, fermented foods, dairy, etc, all happen to be high histamine.

But after treating my suspected SIBO and going on oral progesterone, my symptoms drastically improved and I’ve been able to bring in a lot of variety into my diet. While I still need to avoid the highest histamine foods, I’m now able to eat many more foods in moderation. I also react to several foods that are considered low histamine, so it’s not just histamine that is a problem for me but I’m not sure if it’s oxalates or salicylates or something else.

Something that’s helped is buying frozen fruits and veggies, and eating a spoonful of a different one alongside each meal (not for the full meal, but in addition to my meal). This helps limit my reactions to my trigger foods by keeping it to a bite or two, while also helping me feel emotionally satisfied.

Limiting my exposure to products

I basically cut out most skincare and cleaning products and only use the necessities. See my page here for more details on this.

Changing my lifestyle

At my worst with MCAS, I would have flares when having sex with my boyfriend, when going in the sun, painting (my favorite hobby!), when watching thrillers or movies that put me on edge (and into fight-or-flight). Luckily, I’m able to do most of these things again, but I did have to drastically change the way I lived for about a year.

There is hope

With any chronic illness, the grief that we can feel is overwhelming as we watch our hobbies, plans, and dreams get swallowed up by symptoms. When my MCAS symptoms first came on, I was already in an incredibly difficult moment of my life having just gotten diagnosed with endometriosis and had major 2 surgeries within 4 months. The feelings of despair were so immense that I had intrusive thoughts of unaliving myself. It’s so important to get the mental health support we need. If you find yourself in a similar situation, please reach out to a professional or to a loved one for help.

I was very lucky to find a blog of a girl living with MCAS (I’d link it but she’s taken it down since then) which talked about how changing your diet and lifestyle in accordance to your own personal triggers can make this condition survivable, and eventually, you’ll be able to build a life around the condition. “There’s hope,” she said. And her words stuck with me through multiple episodes of anaphalysis, dizzy spells I couldn’t stand up from, and migraines that made me forget how to speak.

For me, it felt unsurvivable, but I made it through the worst year of my life. While I still have many triggers and have to carefully watch my diet and lifestyle, I’m not having a constant reaction to everything anymore nor anaphylaxis. There are days when I overdo it in terms of histamine in my food or the activities I do, but most days my symptoms are now low. If you are dealing with MCAS, I can relate to how challenging, awful and devastating it is. Hang onto that hope.

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