How to Test for Histamine Intolerance: What Blood Tests Can and Cannot Confirm

No single blood test confirms histamine intolerance. What plasma histamine and DAO activity testing actually measure, why the workup is a supervised elimination and reintroduction, and how mast cell activation syndrome differs.

Medically Reviewed By: Rhonda Collins, FNP-C | September 18, 2026 | 9 min read

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Quick Summary

No single blood test confirms histamine intolerance. A plasma histamine test measures how much histamine is circulating in your blood at the moment of the draw, which rises when mast cells and basophils release their granules during an allergic or mast cell reaction. A serum diamine oxidase (DAO) test measures the activity of an enzyme that breaks histamine down. Neither has been established as a diagnostic test for histamine intolerance. The German, Swiss, and Austrian allergy societies’ guideline on reactions to ingested histamine states that “measurement of DAO activity in serum has no diagnostic value” and that “there are still no reliable laboratory tests that can be used to confirm or reject the diagnosis.” Source: Allergologie Select, 2021.

What the workup actually looks like: a clinician takes the history, excludes the conditions that produce the same symptoms, and then supervises a short low-histamine phase followed by a structured reintroduction to see whether food is really the trigger.

Can a blood test confirm histamine intolerance?

No. Histamine intolerance has no validated biomarker, so no blood test can confirm it or rule it out. A 2024 review in Nutrients states that “there are no specific direct tests that can be used to determine histamine intolerance” and that it “remains a disease diagnosed through clinical exclusion.” Source: Nutrients, 2024.

That is worth being precise about, because tests marketed for this question do exist. They measure something real, either histamine in plasma or DAO enzyme activity, but the measurement has not been shown to separate people who have histamine intolerance from people who do not. A result is one input your clinician reads alongside your symptom history. It is never the answer on its own, in either direction.

What a plasma histamine blood test actually measures

A plasma histamine test measures histamine circulating in your blood at the moment the sample is drawn. Histamine is released mainly by mast cells and basophils, so the test is used to help evaluate “allergic signs and symptoms, such as anaphylaxis” and “may assist in diagnosing and monitoring of mast-cell activation disorders.” Source: ARUP Laboratories.

Two practical constraints decide whether the number means anything:

• Timing. Histamine rises and falls quickly after a reaction. A sample drawn during or shortly after symptoms carries information; a convenience draw on a calm day, weeks later, generally does not.
• Handling. The plasma has to be separated within about 20 minutes of collection and frozen immediately, and hemolyzed or lipemic samples are rejected outright. Source: ARUP Laboratories.

Mito’s Histamine Blood Test product page carries the current timing and preparation guidance for that specific test.

A plasma histamine result is not a diagnosis of histamine intolerance. An elevated value does not establish the condition, and a normal value does not exclude it. What an elevated value supports is that histamine was released around the time of the draw.

Why serum DAO activity is not the answer

Diamine oxidase (DAO) is one of the two enzymes that degrade histamine in the body, alongside histamine N-methyltransferase (HNMT). The appeal of measuring it is obvious: if low DAO activity let dietary histamine accumulate, a blood level ought to show it.

The evidence has not supported that. The 2021 allergy society guideline is direct: “Measurement of DAO activity in serum has no diagnostic value.” It notes that using DAO-specific monoclonal antibodies, “it was not possible to detect relevant amounts of DAO in serum,” while DAO was readily detectable in tissues such as kidney, intestine, and placenta, an observation that “strongly calls into question the significance of a measurement of DAO in serum.” Source: Allergologie Select, 2021. The 2024 Nutrients review reaches a similar place from the other direction: DAO’s “reference value to diagnose histamine intolerance has not been clearly defined,” and intra-subject variability, such as time of day, “limits its robustness.” Source: Nutrients, 2024.

Mito does not offer a diamine oxidase (DAO) enzyme activity blood test. We are telling you that rather than routing you to something adjacent, because the honest answer to “which test confirms histamine intolerance” is that no blood test does.

How histamine intolerance is actually worked up

Because no laboratory test confirms histamine intolerance, the workup is clinical. It has two parts.

First, exclude what else it could be. Histamine intolerance is a diagnosis of exclusion, so a clinician looks for the conditions that produce the same flushing, headache, digestive symptoms, or hives, including IgE food allergy and mast cell disorders. Source: Nutrients, 2024. The symptom overlap is genuinely large, which is covered in more depth in hidden food allergies and intolerance symptoms.

Second, run a structured dietary trial. The 2021 guideline describes three phases: a restriction phase of roughly 10 to 14 days, a test phase of up to about 6 weeks in which suspected foods are reintroduced in a targeted way, and then a long-term diet built around your individual tolerance. Source: Allergologie Select, 2021.

Two honest caveats belong with that pathway.

It is the pragmatic approach in the absence of a validated biomarker, not a validated reference standard, and a blinded challenge frequently fails to confirm the suspicion. The same guideline reports that while 39 of 56 patients clearly responded to histamine in peppermint tea in an open provocation, “none of these reactions were reproducible in double-blind, placebo controlled challenges.” Source: Allergologie Select, 2021.

Do it with a clinician and, where you can, a dietitian. The guideline’s stated primary goal is “to prevent patients, by means of expert nutritional counseling, from following diets that lead to unnecessary dietary restrictions and thereby reduction in quality of life.” Source: Allergologie Select, 2021. A long, unsupervised elimination diet is its own harm, and the suspicion alone often drives one.

Histamine intolerance is not an IgE food allergy

These are different mechanisms, and confusing them is the most common reason people order the wrong test. A food allergy is “an abnormal immune system reaction to certain foods,” and an allergy blood test “measures the amount of allergy-causing antibodies called immunoglobulin E (IgE).” Source: MedlinePlus. A food intolerance is different: as MedlinePlus puts it, “an intolerance is not an immune system reaction.” Source: MedlinePlus.

The consequence for testing is direct. Specific IgE blood testing and skin prick testing detect IgE sensitization to a particular allergen. They do not detect histamine intolerance. A clean allergy panel neither rules histamine intolerance in nor out, and a positive one tells you about an antibody, not about how your body handles dietary histamine.

If IgE allergy is genuinely on the table, that is a different workup with different tests: how to test for food allergies covers what IgE and IgG testing each do and do not reveal, and skin prick test vs blood test for allergies compares the two methods. For pollen, dust, mold, and pet triggers rather than food, start with how to test for environmental allergies.

Mast cell activation syndrome is a different condition

Mast cell activation syndrome (MCAS) is a distinct condition from histamine intolerance and should not be treated as another name for it. MCAS has published consensus criteria: episodic typical mast cell related symptoms affecting more than one organ system, an event-related rise in serum tryptase, and improvement on drugs that target mast cell mediators. The authors of those criteria warn that “the diagnosis of MCAS is being applied currently to patients with unresolved complex medical problems after extensive medical evaluations, and a substantial number of these patients do not meet the diagnostic criteria for MCAS.” Source: J Allergy Clin Immunol, 2018.

This is where tryptase has an established role, and histamine does not. Tryptase is “the most abundant granule-derived serine protease that is mainly produced by mast cells” and to a much lesser extent by basophils. Source: Diagnostics, 2023. It is read as a comparison, not as a single number:

• An acute sample drawn after the event, ideally 30 to 120 minutes after symptoms start, which is when the level peaks.
• A baseline sample drawn at least 24 hours after the episode has fully resolved.
• The consensus threshold: a rise of 20% over that individual baseline plus 2 ng/mL, within a 4-hour window after the reaction. Source: J Allergy Clin Immunol, 2018.

Even when that comparison does show mast cell activation, “no conclusion can be drawn about the mechanism (IgE-mediated or non-IgE-mediated) responsible” for it. Source: Diagnostics, 2023. A tryptase result does not test for histamine intolerance, and a histamine result does not diagnose MCAS. If mast cell activation is the real question, Mito’s Tryptase Blood Test product page has the collection timing for that test.

Test This with Mito

Mito does not sell a histamine intolerance test, because no blood test confirms histamine intolerance. Mito also does not offer a diamine oxidase (DAO) enzyme activity blood test. What Mito does offer are two tests that answer narrower questions, and it is worth being clear about which question each one answers:

• Histamine Blood Test: whether an acute episode involved histamine release, subject to the timing and handling constraints above. It does not confirm or exclude histamine intolerance.
• Tryptase Blood Test: for working up suspected mast cell activation or anaphylaxis, where the acute and baseline comparison described above is the point of the test.

Both product pages carry current pricing, eligibility, and availability. If what you actually need is allergy testing rather than either of these, what allergy testing costs breaks down the price of the IgE options. Whichever you order, agree the plan with a clinician first, because the timing of the draw is what decides whether the result means anything.

Key Takeaways

• No blood test confirms histamine intolerance. There is no validated biomarker for it.
• A plasma histamine result reflects histamine circulating at the moment of the draw. Elevated does not establish histamine intolerance, and normal does not exclude it.
• Serum DAO activity has no established diagnostic value for histamine intolerance, and Mito does not offer a DAO enzyme activity blood test.
• The workup is clinical exclusion plus a supervised low-histamine phase and structured reintroduction, done with a clinician and ideally a dietitian.
• IgE food allergy, histamine intolerance, and mast cell activation syndrome are three different things. Allergy testing detects the first, tryptase helps with the third, and neither confirms the second.

Medical Disclaimer

This guide provides general education, not personal medical advice, diagnosis, or a treatment plan. Your clinician should guide test selection, any dietary restriction, and care based on your history and results. Do not start a prolonged elimination diet on your own, and seek urgent medical care for any severe allergic reaction.

References

1. Reese I, et al. Guideline on management of suspected adverse reactions to ingested histamine. Allergologie Select. 2021;5:305-314.
2. Jochum C. Histamine Intolerance: Symptoms, Diagnosis, and Beyond. Nutrients. 2024.
3. ARUP Laboratories Test Directory: Histamine, Plasma.
4. MedlinePlus: Allergy Blood Test.
5. MedlinePlus: Food Allergy.
6. Valent P, et al. Mast cell activation syndrome: Importance of consensus criteria and call for research. J Allergy Clin Immunol. 2018;142(3):1008-1010.
7. Beyens M, et al. Diagnostic Significance of Tryptase for Suspected Mast Cell Disorders. Diagnostics (Basel). 2023;13(24):3662.