Histamine Intolerance: Everything You Need To Know

Do you live in Ottawa? Are you looking to find out about Histamine Intolerance?

If so, you are in the right place.

Today I will write about what it is, the causes, symptoms, testing and treatment of Histamine Intolerance.

In This Article:

Let’s start with what Histamine is.

What Is Histamine?

Histamine is a chemical associated with your immune, digestive, and central nervous systems.

As a neurotransmitter, it conveys essential messages from your body to your brain.

It is also an ingredient of stomach acid that helps you digest food in your stomach.

You might be most intimate with Histamine as it associates with the immune system.

If you’ve endured seasonal or food allergies, you may have noticed that antihistamine medications such as Zyrtec, Allegra or Benedryl quickly relieve your symptoms.

This process occurs because Histamine’s role in the body is to cause an immediate inflammatory response.

It serves as a warning to your immune system of any potential threats.

Histamine causes your blood vessels to widen or dilate so that your white blood cells can quickly find and attack an infection.

Histamine is released by mast cells in the skin and the gut lining.

So if a mosquito bites you, the histamine release will cause a red, itchy feeling on the skin.

If you eat a food that you are anaphylactic, the histamine release may create swelling in the lips and tightening of the throat.

If you eat sensitive food, the histamine release may create digestive symptoms such as heartburn or acid reflux.

Some cells in the skin and the gut lining release enzymes, predominately Diamine Oxidase (DAO) that break down Histamine when it is no longer required.

If you have inflammation in the gut, this can slow the release of DAO and lead to excess Histamine.

Because it gets into your bloodstream, the excess Histamine can affect your lungs, skin, brain, reproductive organs and cardiovascular system, leading to a broad range of symptoms that can make it difficult to diagnose the underlying cause.

Excess Histamine in the body due to poor breakdown in the gut is known as histamine intolerance.

Let’s now look at what causes inflammation in the gut.

Causes Of Gut Inflammation

  1. Small Intestinal Bacterial Overgrowth (SIBO)
  2. Small Intestinal Fungal Overgrowth (SIFO)
  3. Food Sensitivities.
  4. Parasites
  5. Dybiosis or Bacterial Imbalance.
  6. Inflammatory Bowel Disease, including Crohn’s and Ulcerative Colitis.

Apart from gut inflammation, there are a few other reasons for low DAO production.

Other Reasons For Low DAO

Other reasons for the low production of DAO include the following:

  1. DAO-blocking foods: alcohol, energy drinks, and tea
  2. Genetic mutations (common in people of Asian descent)
  3. Medications: Non-steroidal anti-inflammatory drugs (ibuprofen, aspirin), Antidepressants (Cymbalta, Effexor, Prozac, Zoloft), Immune modulators (Humira, Enbrel, Plaquenil), Antiarrhythmics including Propranolol, Metoprolol, Cardizem, and Norvasc, Antihistamines including Allegra, Zyrtec, and Benadryl, and Histamine (H2) blockers including Tagamet, Pepcid, and Zantac.

Although histamine blockers, a class of acid-reducing drugs, seem like they would prevent histamine intolerance, these medications can deplete DAO levels in your body.

Let’s now look at the typical symptoms of histamine intolerance.

Typical Symptoms of Histamine Intolerance

  1. Headaches/migraines
  2. Difficulty falling asleep, easy arousal
  3. Hypertension
  4. Vertigo or dizziness
  5. Arrhythmia, or accelerated heart rate
  6. Difficulty regulating body temperature
  7. Nausea, vomiting
  8. Abdominal cramps
  9. Flushing
  10. Nasal congestion, sneezing, difficulty breathing
  11. Abnormal menstrual cycle
  12. Hives
  13. Fatigue
  14. Tissue swelling
  15. Joint pain
  16. Brain Fog
  17. Anxiety

Testing for Histamine Intolerance

Blood Testing

You can ask your doctor to test for histamine and DAO levels. A high ratio of Histamine to DAO means excess Histamine in your body.

I use presenting symptoms and muscle testing to determine excess Histamine.

How to Treat Histamine Intolerance?

Treating Histamine is a stepwise approach including the following:

Step 1: Reduce Histamine and Relieve Symptoms

Following a low fodmap diet has been shown to lower histamine levels and symptoms.

At the beginning of step 1, you may need to consider high histamine foods if they elevate symptoms.

Step 2: Treat The Gut

You need to resolve the underlying issue in the gut, whether it is SIBO, SIFO, Food sensitivities, parasites, dysbiosis or IBD.

Step 3: Resolve Any Current Stress and Past Emotional and Physical Trauma

Step 4: Heal The Gut Lining

Going on a low fodmap diet for 3-4 months after completion of treatment has been shown to aid in the repair of the gut lining.

Now It’s Over To You

Do you experience symptoms of heartburn, headaches and hives?

Have you considered you might have Histamine intolerance?

Leave me a comment below.

Do You Need Help?

If you need help, I suggest you book a free functional medicine discovery session with me to determine whether my functional medicine approach fits your child’s needs.


The information provided on this website is for educational purposes only and is not intended to diagnose or treat any disease. Please do not apply this information without first speaking with your doctor.


  1. Histamine Intolerance Food List Where can I obtain it. I have many of the symptoms listed especially chronic vertigo and sleep issues.

  2. Hi George,

    Here is the list I give my clients.


    Hope it helps.


  3. hi I have most of them too , I have hard time breathing sometimes headaches and one more

  4. What’s the best natural anti-histamine?
    Kidney (gland)?

    1. Hi Monika,

      Thanks for your comment.

      I find Quercitin plus Vitamin C works very well.


  5. Is there any lab in Ontario that I can get a test for blood histermine levels and also DAO levels?

    1. No.

  6. I’ve had a mystery illness for 2.5 years. My symptoms are breathing difficulty the worsens as the day goes. 24/7 sore throat and stuffy nose. I’ve had countless tests ran. I tried the acid watchers diet for a month with no improvement. I just started a low histamine diet to try to see if this helps. But my question is… you say to do it for a month and then reintroduce foods. What if I don’t see an improvement in a month? Is it safe to say that histamine isn’t the issue? But then you go on to say that for treatment, to eat a low histamine diet for 1-3 months.

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