Histamine Intolerance: Everything You Need To Know

Do you endure unexplained headaches or migraines? What about difficulty falling asleep? Do you react badly to mosquito bites? Do you experience irregular periods? If you said yes to any of these questions, then you could have a histamine intolerance.

What is histamine?

Histamine is a chemical associated with your immune, digestive, and central nervous systems. As a neurotransmitter, it conveys important 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 allergies or food allergies, you may have noticed that antihistamine medications such as Zyrtec, Allegra or Benedryl provide quick relief of 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. The histamine accumulation is what gives you a headache and leaves you feeling flushed, itchy and miserable. This process is part of the body’s natural immune response, but if you don’t break down histamine correctly, you could develop what we call histamine intolerance.

Because it travels throughout your bloodstream, histamine can affect your digestive tract, lungs, skin, brain, and cardiovascular system, leading to a broad range of symptoms that can make it difficult to diagnose the underlying cause.

Typical symptoms of histamine intolerance

  1. Headaches/migraines
  2. Difficulty falling asleep, easily arousal
  3. Hypertension
  4. Vertigo or dizziness
  5. Arrhythmia, or accelerated heart rate
  6. Difficulty regulating body temperatureAnxiety
  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

What Causes High Histamine Levels?

  1. Allergies (IgE reactions)
  2. Small Intestinal Bacterial Overgrowth (SIBO)
  3. Increased Intestinal Permeability or Leaky gut
  4. Parasites
  5. Gastrointestinal bleeding
  6. Fermented alcohol like wine, champagne, and beer
  7. Diamine Oxidase (DAO) deficiency
  8. Histamine-rich foods
  9. In addition to the histamine made in your body, there is also a mixture of foods that naturally contain histamine, create the release of histamine, or block the enzyme that breaks down histamine, Diamine Oxidase.

How do I break down histamine?

Once made, histamine is either stored or broken down by an enzyme. Histamine in the central nervous system is broken down primarily by histamine N-methyltransferase (HMT) while histamine in the digestive tract is broken down mainly by diamine oxidase (DAO). Though both enzymes play a significant role in histamine break down, the American Society for Clinical Nutrition found that DAO is the primary enzyme responsible for breaking down ingested histamine. So if you’re deficient in DAO, you likely have symptoms of histamine intolerance.

Causes of Low DAO

  1. Gluten sensitivity
  2. Intestinal Permeability
  3. SIBO
  4. DAO-blocking foods: alcohol, energy drinks, and tea
  5. Genetic mutations (common in people of Asian-descent)
  6. Gut Inflammation from Crohn’s, ulcerative colitis, and inflammatory bowel disease.
  7. 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.

Testing for Histamine Intolerance


Remove the above high histamine foods for 30 days and reintroduce them one at a time.

Click here to download a free copy of my Histamine Intolerance Food List

Blood Testing

You can ask your doctor to test for histamine and DAO levels. A high ratio of histamine to DAO means that you are ingesting too much histamine and that you don’t have sufficient DAO to break it down.
Trial of DAO

If testing is unavailable to you, you could only try a diet low in histamine and add DAO supplementation at each meal. If your symptoms resolve, you could have reduced DAO.

How to Treat Histamine Intolerance?

  1. Remove the high histamine foods for 1-3 months.
  2. Add in a supplement of DAO by taking two pills at each meal. Most importantly, find the root cause of the histamine intolerance. If you’re on a medication that is causing the intolerance, working, with your physician, to wean off of these medications is essential. The main reasons I see in my practice are SIBO and gluten intolerance, which cause a leaky gut.
  3. If you currently have histamine intolerance, you may not have to avoid these foods permanently. It can be a short-term answer until your histamine or DAO levels revert to their optimal ranges. Depending on your personal circumstances, you may discover that you tolerate some foods better than others, so I encourage you to stay positive as you learn priceless information about your body!

If you have any questions about this article either post them in the comments section below or email using the form on my contact page.


This article in not intended to provide medical advice, diagnosis or treatment.


  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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