I’ve been told, by a number of doctors, that it takes, on average, a decade to diagnose someone with a mast cell disorder. I personally consider histamine intolerance to be a mast cell disorder. It took me almost 30 years and 68 doctors to get to histamine intolerance, and then another three years and two doctors to get to mast cell activation disorder.

No matter the diagnosis, I believe, and have seen, that histamine/mast cell disorders, are totally manageable through dietary changes, a healthy but low impact exercise regime, regular meditation and stress management, and a whole heap of positivity – with or without meds. I don’t take meds.

Don’t just take my word for it, check out my testimonials page and my interview with leading mast cell expert Dr Castells (on the role of diet and exercise in mast cell disorders).

Here’s how I added foods back to my diet after the elimination phase left me with only a handful of “safe” foods.

DIAGNOSING HISTAMINE INTOLERANCEDiagnosed by: nutritionists, GPs/primary care physicians, functional/integrative medicine doctors.You’ll have a tough time convincing: allergists and immunologists that it exists.Best countries for diagnosis: Germany, Austria, UK.Histamine Plasma

What it is: the level of histamine currently found in your blood.

Why measure it: histamine intolerance is thought to be too much histamine in the body.

Reliability: given that histamine is found in the body as well as food, and is released by mast cells (white blood cells) as needed to wake us up, control appetite and metabolism, as neurotransmitter, and much more, any doctor worth their salt will tell you that histamine fluctuates wildly in your body, and as such this is not a reliable test of your average histamine level.

DAO (diamine oxidase)

What it is: DAO is an enzyme found in the gut. It’s responsible for degrading histamine there.

Why measure it: the theory is that low DAO makes it hard/impossible to clear histamine from the body, leading to histamine intolerance/symptoms of high histamine.

Reliability: DAO is one of two histamine-degrading enzymes we know of (HNMT being the other), therefore just relying on DAO as a measure isn’t likely to give us the full picture. Throw in the fact that DAO also fluctuates wildly, and that we don’t know where else, other than the gut, DAO might live, and whether we’re even measuring it in the right spot! I also always point out to people – if you’re not eating high histamine foods anymore, why is there still so much left (supposedly) for DAO to eliminate? Read on for the answer.

Elimination diet

What it is: a four-week elimination of all foods on the high histamine lists.

Why try it: the theory is that no matter the test results, if eliminating these foods makes you feel better, you have your answer.

Reliability: let’s start with the fact that all high histamine food lists contradict each other, that many high histamine foods are also junk/bad for you generally, so cutting them out would make most people feel better anyways, and that restricting foods is rarely healthy. Add in that most people, sadly, are told that they must continue restricting these foods, thereby starving themselves of nutrition, thereby further weakening their body and ensuring they will continue to react.

Histamine prick test

A study on the prick test method to print for your doctor.

What it is: Austrian docs figured out that injecting patients with histamine causes a significant reaction (when compared to controls) and as such is a reliable way to diagnose patients with histamine intolerance.

Why try it: my allergy scratch tests came back negative for years, but docs always commented on my unusually severe response to the control (pure histamine!). I would be very careful if you have ever had major reactions and good luck convincing a doc to do it for you!

Reliability: I can’t really speak to this one as I don’t have enough information on it yet.

Ok, a final word on why all these tests must be taken with a pinch of salt: histamine, an inflammatory agent in the body, is contained within mast cells. Mast cells, white blood cells that are an integral part of our immune system, also contain dozens of other inflammatory elements, that are not addressed in the tests above. I continue to say, that focusing on just histamine as a method of diagnosis, treatment, or diet, is the BIGGEST mistake anyone can make. I made it myself, for many years, and continued to get sicker.

Once I researched why mast cells release too much histamine in the first place, I understood I needed to widen my scope to inflammation in general, rather than just histamine. I talk about this in depth in the Anti-Cookbook.


Diagnosed by: functional/integrative medicine doctors, immunologists, haematologists, some allergists (rare though), some GPs (also very rare).

You’ll have a tough time convincing: European doctors who deal in mastocytosis, nutritionists (may fob you off with an inaccurate diagnosis based on symptoms).

Best countries for diagnosis: United States, Spain (Virgen del Valle Hospital in Toledo).

Mast cell activation syndrome is usually diagnosed (mainly) on the basis of symptoms and exclusion of all other possible diagnoses. Mast cell activation disorder usually requires a number of positive tests (see below).

Diagnosing mast cell activation syndrome

“Diagnosis of MCAS is often difficult for many reasons, principally the cognitive challenge it poses to the diagnostician. The average physician is capable of considering only a handful of clinical elements at a time when attempting to recognize diagnostic patterns of presentation (e.g., fever, night sweats, and hemoptysis suggest a possibility of tuberculosis).

Temporal factors are important to human cognition, too. The human mind is increasingly challenged at recognizing patterns when events occur with less temporal regularity and less temporal proximity to one another. Furthermore, repetition of presentation is key for diagnostic efficiency. The physician who repeatedly sees the same set of elements present in the same temporal pattern will be able to recognize the same pattern more efficiently in the future.

MCAS, though, seems almost artificially engineered to confound diagnosticians. Its great menagerie of underlying activating mutations, combined with the mast cell’s normal function of producing and releasing a cornucopia of highly potent mediators (each with multiple direct and indirect, local and remote effects), ensures a tremendous range of clinical presentations. Once a full history is obtained, it is evident that the average MCAS patient presents with a large number of symptoms and findings, and many of these presenting elements wax and wane over time periods ranging from minutes to years, often with no clear temporal relationship to one another.” – Dr Afrin.

Criteria for diagnosing mast cell activation

(You could just print this document off and take it to your doctor)

Mast cell activation syndrome is mainly diagnosed on the basis of symptoms:

As per Dr Afrin:

(1)…the general presenting motif of MCAS is chronic multisystem polymorbidity, generally of an inflammatory theme and with assorted elements waxing and waning over time, sometimes in synchronization with one another but more often cycling with different periods and amplitudes.

(2) When there are symptoms and findings not classically expected with, or not easy to attribute to, the patient’s established diagnoses, alternative diagnoses must be entertained to account for these “leftover” elements, and given the universal truth of Occam’s Razor, it becomes more likely that the same diagnosis that accounts for the leftover elements also accounts for the established diagnoses.

(3) The range of mast cell mediators and their effects is so great that “unusual” presentations actually become de rigeur. That is to say, although any given unusual presentation remains unusual, the full set of unusual presentations constitutes a large fraction of the total set of presentations. Thus, when the clinician recognizes an “unusual,” “odd”, “weird”, “bizarre,” or “strange” element in the patient’s presentation–e.g., “allergies” to typically innocuous medications, migratory rather than dependent edema, severe and highly variable hyperferritinemia not attributable to the patient’s transfusion and chelation history, etc. – his “MCAS radar” should go on alert. The presence of an unusual element in the presentation by no means establishes a diagnosis of MCAS, but it sometimes can be the first spark toward lighting a fire of recognition.

Thus, the largest impediment to diagnosing MCAS may simply be suspecting it.

As per Dr Theoharides

(From a recent presentation)

(1) Dermatologic: flushing, pruritus, urticaria pigmentosa, angioedema, dermatographism (sometimes)

(2) Respiratory: wheezing, sore throat

(3) Cardiovascular: chest pain, hypotension, tachycardia

(4) Gastrointestinal: abdominal pain, nausea, vomiting, diarrhea, bloating, malabsorption, esophagitis

(5) Naso-ocular: nasal stuffiness, pruritus

(6) Neurologic: headache, memory and concentration difficulties/brain fog, paresthesia, peripheral neuropathy

(7) Muscoskeletal: bone/muscle pain, degenerative disc disease, osteoporosis/osteopenia

(8) Systemic: anaphylaxis, fatigue

Diagnosing mast cell activation disorder

All the symptoms and indications above, plus positive:

N-methylhistamine 24 hour urine test

Prostaglandin D2


Tryptase (this doesn’t have to come back out of range, it’s usually done to rule out mastocytosis)


Diagnosed by: functional/integrative medicine doctors, immunologists, haematologists, some allergists (rare though), some GPs (also very rare), dermatologists (mostly in the case of cutaneous mastocytosis or urticaria pigmentosa).

You’ll have a tough time convincing: nutritionists (may fob you off with an inaccurate diagnosis based on symptoms), almost any other kind of doctor.

Best countries for diagnosis: United States, Spain (Virgen del Valle Hospital in Toledo), United Kingdom.

Diagnosing mastocytosis

As per Dr Afrin

(1) Multifocal or disseminated dense infiltrates of mast cells in bone marrow biopsies and/or in sections of other extracutaneous organ(s) (CD117-, tryptase-, and CD25-stained)

(2) Unique constellation of clinical symptoms secondary to a pathological increase in mast cell activity (mast cell mediator release syndrome)

Minor criteria:

(1) Mast cells in bone marrow or other extracutaneous organ(s) show abnormal morphology (>25%) in bone marrow smears or on histological examination

(2) Mast cells in bone marrow express CD2 and/or CD25

(3) Detection of genetic alterations in mast cells from blood, bone marrow, or extracutaneous organs, which have been confirmed to result in an increase in the activity of affected mast cells.

(4) Evidence of a pathological increase in mast cell activity through detection of an elevated level of at least one sensitive mast cell-derived mediator, i.e., tryptase, heparin, histamine, PGD2, chromogranin A, leukotrienes (and their assorted metabolites) in blood and/or urine

The Anti-cookbook, while it doesn’t treat any conditions, due to its high nutrient, antihistamine and anti-inflammatory ingredients, has been instrumental in helping me feed myself on a limited diet. It features a six page list of antihistamine and anti-inflammatory foods. It comes in regular and Paleo. 

The Low Oxalate Cookbook features antihistamine and anti-inflammatory rich recipes. 

Take a peek at my low histamine and antihistamine cookbooks for more high nutrient recipes. If you’ve found this information useful I’d appreciate your support (at no extra cost to you!) – please check out my online store for your health foods, supplements, kitchen items and beauty product purchases. Affiliate sales through my online store go towards maintaining the website, funding travel to interviews and purchasing all the lovely foods for my free online recipes.

You’ll find these items in the “Shop with us” drop down menu on my homepage.  

Please don’t forget antihistamine, pain killing foods can still hurt us, so please always check with your doctor before adding new foods to your diet. 

My first post on diagnosing histamine intolerance….
PART 1Your first steps in diagnosing Histaminosis (high histamine & low diamine oxidase – sometimes called Histamine Intolerance).My heart goes out to the hundreds of people I come across in allergy forums looking for answers, muddling through on their own because they either can’t afford a proper doctor, or because they believe paying for medical care out of pocket is wrong. I repeat myself a lot out there, so I’ve put together a little flowchart that I hope will help.STEP 1If you are experiencing symptoms of: IBS, Crohn’s Disease, Gastrointestinal distress, irregular heartbeat, dizziness, nausea, vomiting, migraine, anxiety, depression, mania, rash, hives, urinary tract issues and frequency, uterine cramping, yeast-like infection, blurred vision, low blood pressure when getting up, pins and needles in feet, feeling of electricity in your fingers, feet or legs, neuropathy, tinnitus, suddenly falling asleep, convulsions, syncope, sinus infection (with negative culture, don’t let them give you antibiotics if it is!!), blocked nose, persistent sore throat, all with negative culture or coming up empty in diagnostic tests…STEP 2Don’t allow them to give you medication anyway! That could make you worse*. I’ll tell you why in a bit. So proceed to…STEP 3Keep a food diary for a few weeks. If you notice your symptoms are related to food, remember that symptoms can take up to two days to appear, go to….STEP 4Find a doctor to do IgE allergy tests. If they are negative, don’t panic, go to….


Find a specialist who knows what biogenic amines are: Histamine, Tyramine, Tryptamine, Glutamine, Putrescine, Spermidine, Cadaverine and others. You can test negative for allergies but have a biogenic amine sensitivity or intolerance that could give you all the symptoms listed previously.

BUT make sure he also knows what Diamine Oxidase (DAO) and Monoamine Oxidase (MAO) are before your consult. if he doesn’t, don’t go! These enzymes are responsible for degrading two of the most common, or at least most commonly identified, biogenic amines (Histamine and Tyramine respectively).

Step 6

If your tests come back negative for biogenic amine sensitivity but with high histamine and low DAO, welcome to my club. Histaminsosis or Histamine Intolerance. Get your low histamine diet, hopefully medical trial of synthetic DAO or whatever is on the market that you choose. If it comes back with extraordinarily high histamine, with or without low Diamine Oxidase, you might want to ask about Mastocytosis. But, a decent specialist who specialises in biogenic amine issues would already know this.

If you come back with low MAO or tyramine sensitivity you will likely be given a diet plan and possibly a DAO supplement since Tyramine is also influenced by it.

*There are over 100 medications that can affect the enzymes that degrade Diamine Oxidase alone. Suppressing DAO could lead to higher histamine levels which defeats the purpose. Be aware that even some antihistamines prescribed to lower the histamine suppress DAO!

In part one I outlined the histaminosis (histamine intolerance) diagnosis process with a specialist in histamine and biogenic amines. Here’s how to make it happen with someone who isn’t.Try not calling it an “intolerance”I believe that one of the most important issues our growing community faces is that people are calling this condition an intolerance. If we want doctors to take us seriously then perhaps we should call it by a proper name like Histaminosis which is diamine oxidase blockade and the resulting high histamine. An intolerance is a bit of a weak name for the very serious illnesses that are the result of high histamine. I suggest reading Dirk Budka’s book The Histamine Confusion as a primer on the condition and also to discuss with your doctor.Your doctor isn’t god…They can’t possibly know everything under the sun and frequently deal with hypochondriacs (or worse – ever hear of munchausen’s by proxy?), so help them out by printing out some of the many studies (you’ll find them in the resources section of The Low Histamine Chef).Know your stuffRead, absorb, use a highlighter pen on relevant sections. Use one colour for tests, another for supporting studies (in the references section) and another for your symptoms. Make sure you provide your doctor with a colour coded key at the top of the document. I also suggest making two copies so you can go through them together and not lose your place (or momentum).Be clear about what you wantMake a special note of the tests to be run and point out which famed medical institutions conduct them (Mayo Clinic, Mayr Clinic). Histamine level and diamine oxidase are necessary for a concrete diagnosis. You may want to also point out that these are the symptoms of mastocytosis. This could get the attention of the doctor. Now, you may be referred to an immunologist who wants to diagnose you with masto based on symptoms and or tryptase, but really the best way to diagnose is bone marrow. I suggest insisting on the histamine and diamine oxidase test first. I have friends with “masto” that turned out to be histaminosis.Hold your ground! Make sure you have a checklist of things to address/accomplish with the doc and refuse to budge from his office till you get what you want. Try not to get emotional – they will make a note in your file that will be hard to remove! Be cool, calm and completely together. Lay out your case logically.

Be prepared to accept…

That you may not have histamine intolerance. There are many conditions related to histaminosis (histamine intolerance): mastocytosis, mast cell activation, hypersensitivity disorder, viral infections and a few more.

Or, you could have other biogenic amine issues like low monoamine oxidase (MAO). I have that too!