Histamine Intolerance / Mast Cell Activation Syndrome

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


Dealing with MCAS symptoms, which began a few months after my excision surgery, has been extremely difficult, but by understanding the root causes to my MCAS and HI, I’ve managed to lessen my reactions over the last 2 years.

Getting diagnosed

I have a suspected diagnosis based on my symptoms. 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. There are some tests they can do, like histamine, tryptase, and others, as well as putting you on a trial of H1/H2 histamine blockers for 2 weeks to see if your symptoms improve. However, there are issues with the tests, like 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 1000 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 mast cells 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 found the testing very helpful to rule out other causes to my symptoms, and now that I know something is up with my mast cells, I’ve been focusing on how to calm them down.

Some of the root causes in my case are:

  • hormone imbalance – I am in perimenopause, and taking oral progesterone at night has been very helpful. I also learned through hormones testing and a gene analysis that my body has trouble with phase 2 of estrogen detoxification and began taking supplements to support it.

  • 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, and 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 a 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, perfectionism, and others can put our bodies into an activated state of “danger”.

  • histamine in my food – this may not be a cause per say, but it’s definitely been a huge contributor. Going on a low histamine diet has done wonders. At first, I was ultra-low histamine and had immediate, serious reactions whenever I ate food, even foods that are low histamine. But after working on the previous 3 components above, I’ve been able to loosen up around what I eat. While I’m still low histamine, I’m now able to eat in moderation some higher histamine foods daily. If I have a full on high histamine meal like salmon with spinach and strawberries with vinaigrette dressing (all high histamine foods), well then I have huge reactions, but I can do a few bites of one of those foods if I accompany it with other low histamine foods.

  • toxins and ingredients in common products – like food, this is not a cause per say, but a contributor. I basically cut out most skincare and cleaning products, only use the necessities, and try to find more “natural” versions of them with only a few ingredients. See my page on reducing toxins for more details on this.

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 pretty low. If you are dealing with MCAS, I can relate to how challenging it is. Hopefully some of the resources below can help.

For more info

Related Podcast Episodes

  • Histamine Intolerance (coming soon)
  • Mast Cell Activation Syndrome (coming soon)