Histamine Intolerance and the Mold-Injured Patient

By Dr. Susan Tanner, MD

You probably hear about histamine mostly relating to allergies, as we take “antihistamines” to help control common symptoms, but this is just the tip of the iceberg.  Structurally, histamine is an organic compound. It is involved in local immune responses, but also regulates many functions in the gut. It acts as a neurotransmitter for the brain, spinal cord, and uterus. Histamine is involved in the inflammatory response and has a central role as a mediator of itching. As part of an immune response to foreign pathogens, histamine is produced by basophils and by mast cells found in nearby connective tissues; both are forms of white blood cells. Histamine also increases the permeability of the capillaries to white blood cells and to some proteins. This process is behind many of the effects that histamine has on the body.

What is Histamine Intolerance?

The release of histamine causes blood vessels to swell so that white blood cells can quickly come in to resolve any problems. This is part of the body’s natural immune response. Typically, enzymes (primarily diamine oxidase) will break down histamine after it is released so that it doesn’t build up. But, if the body doesn’t break down histamine properly, it can build up and cause histamine intolerance.

What Are Signs and Symptoms of Histamine Intolerance?

As histamine travels throughout your bloodstream, it can affect your gut, lungs, skin, brain, and entire cardiovascular system. Histamine can contribute to a wide range of symptoms.  Histamine intolerance symptoms are often associated with common allergic responses and symptoms. This can make histamine intolerance difficult to pinpoint or diagnose as the symptoms can affect multiple body symptoms simultaneously and can seem unrelated to a common trigger. Some histamine intolerance symptoms include, but are not limited to the following:

-Abdominal cramps

-Abnormal menstrual cycle


-Arrhythmia, or accelerated heart rate

-Difficulty falling asleep

-Difficulty regulating body temperature






-Nasal congestion, sneezing, difficulty breathing

-Nausea, vomiting

-Tissue swelling

-Vertigo or dizziness

What Are Root Causes of Histamine Intolerance?

1. Diamine oxidase (DAO) underproduction. DAO is an enzyme produced in the gut.  One of its major responsibilities is to break down histamines that are formed in the gut lining.  When underproduced for any reason, elevated levels of histamine occur, especially when the gut is exposed to toxins and/or high histamine foods.

2. Environmental exposures, including mold and mycotoxins. Chemicals that pass through the bloodstream by inhalation or skin contact are absorbed and can hit the gut lining just as an ingested food does. When this occurs, the increased permeability of the capillaries is stimulated to produce more histamines.  Additionally, the exposure to these chemicals and toxins activates another white cell complex, known as mast cells.  Mast cells signal massive production of histamine.  Sounds like mast cells are a bad thing, right? Not necessarily. It is all about balance, as mast cells are there for several purposes and play many important roles in the body which include–

-The production of new blood cells

-Wound healing and tissue repair

-Immune tolerance development

-Maintenance of the blood-brain barrier function

-Protection for the body against invading pathogens

3. Bacterial imbalance of the gut. Not only do some undesirable bacteria and yeast in the gut produce histamine themselves, but their very presence leads to the less than optimal function of the immune lining of the gut itself; it becomes less protective and more reactive.

4. Genetic mutations, such as MTHFR, discussed in previous articles. Along with the many other features of these genes, the management of histamines is another!

Histamine Intolerance and Mold-Injured Patients

Mold and mycotoxin exposure can create a chronic inflammatory response in some people where the immune system senses the threat, launches an immune response to attack and remove that threat, but because the exposure continues or the body is unable to detoxify properly, the inflammation never ceases. When chronic inflammation occurs, so does elevated histamine, autoimmunity, and a host of other symptoms and issues. The inflammation of capillaries, as I briefly discussed above, also occurs. Capillaries are the tiny arteries that deliver oxygen to tissues. When capillaries become inflamed, essentially tissues then become oxygen-deprived. This results in symptoms such as headaches, muscle aches (myalgia), and overall fatigue that are also indicative of histamine intolerance. The kicker is that once this has begun happening, the amount of mold spores necessary to create immune and histamine activation is quite small. So, not only are mold patients often becoming sicker and sicker from the chronic inflammatory response and depleted immunity to other pathogens, but they are also becoming more and more sensitive and intolerant to mold and everything else for that matter! This is why, even after recovering, mold-sensitized patients must be diligent about mold hygiene and maintenance of their indoor environments to stay well.

Addressing Histamine Intolerance

First and foremost, it goes back to the adage that we repeat over and over in our articles:  Clean air, clean water, clean food.   If continually exposed to mold, mycotoxins, or other chemicals, and especially if the genetic set up is there to form histamines, then this is a cycle that cannot be managed well without removing the offending players.  Mold must be removed from the living areas.  Clean water without chemicals must be consumed. Foods that provoke the release of histamines must not be consumed.

Getting the gut back into balance is a long-term goal and tends to help mitigate high histamine response very well over time.  Gut balance includes probiotics and immune support of the gut to help get the microbiome back into order.  There is a class of digestive enzymes containing DAO that is extremely helpful in reducing histamine in the breakdown of foods.  Use of these may even allow a less stringent diet, although initially, I ask patients to adhere to the low histamine list. The following is a list of known high-histamine foods, but unique to individuals is their response to other specific foods, which may adapt and switch over time if the underlying gut imbalance is not addressed.

High-Histamine Foods to Avoid

The biggest offenders are usually any type of fermented foods – during fermentation, the bacteria produce histamine. Leftover meat can also be problematic since microbial action increases histamine levels as the meat sits. Some high-histamine foods to avoid are as follows:

-All fermented alcoholic beverages especially wine (white and red), beer, champagne, sherry, and all other alcoholic drinks – even if the alcohol has been cooked off.

-Cured meats including bacon, dried cured sausages, hot dogs, luncheon meats, pepperoni, and salami.


-Smoked or canned seafood and seafood that has been improperly handled or stored for too long.

-Certain fish like anchovies, bonito, butterfly kingfish, dried milkfish, herring, mackerel, mahi-mahi, marlin, pilchards, saury, scads, smooth-tailed trevally

-Tuna and sardines – In these, the amount of histamine varies between different species with some containing no histamine at all.

-Fish paste (like anchovy paste), and shrimp paste

-Fermented foods like kefir, kombucha, sauerkraut, yogurt, fermented sausages, fermented ham, vinegar, soy sauce, and any fermented soy product

-Vinegar-containing foods such as mayonnaise, pickles, and preserved olives

-Soured foods like buttermilk, soured bread, sour cream, and sour milk

-Dried fruits like apricots, dates, figs, raisins, prunes

-Most citrus fruits

-Nuts like cashews and walnuts


-Cheeses like Camembert, cheddar, Emmental, Gouda, Harzer (German sour milk cheese), Parmesan, Swiss cheese and Tilsit or Tilsiter cheese






-Tomatoes and ketchup

Obviously, many of these are very healthy foods, but initially, if you suffer from the severe histaminic response, then elimination while dealing with underlying factors is helpful.

There is a host of other foods that don’t contain histamine but may stimulate the production of it.  This list is long and is unique to the individual.  Rather than writing it all out here, I would suggest a food diary to track symptoms with foods that you eat, or getting an IgG blood test for food sensitivities. Speaking of testing . . .

What Tests Can Help Determine if Histamine is a Problem?

The first, of course, is not a test, but a list of your symptoms; this list can be quite long.  I suggest looking at all of these to see if greater than three are present before assuming that histamines may be a cause. Symptoms by body part or symptom include the following:

Eyes – Redness, itching, burning, watery

Nose – Runny, itching, sneezing, seasonal allergies

Mouth – Swelling, itching

Skin – Swelling, rashes, itching, hives (can be localized or all over the body)

Throat – Swelling or ‘throat tightening’

Lungs – Coughing, wheezing

Digestive tract – Heartburn, indigestion, reflux, cramps, diarrhea

Vascular – Headaches, fatigue, confusion, irritability, symptoms resembling those of anxiety or panic attack, loss of consciousness unexplained by other causes

Cardiovascular – Drop in blood pressure (especially when you stand up quickly), chest pain, increased heart rate, or ‘racing heart’

For actual lab tests to aid in the diagnosis, blood tests that test for both histamine and DAO levels can be helpful. Moreover, you can also run a serum tryptase test to assess mast cell activation syndrome. Tryptase is an enzyme that is released, along with histamine and other chemicals, from mast cells when they are activated as part of a normal immune response as well as in allergic (hypersensitivity) responses. This test measures the amount of tryptase in the blood. In some cases, tryptase levels will be persistently high in persons with mast cell activation disorders, in which mast cells become activated without apparent allergies or other reasons.

What Foods Can I Eat While I am Figuring This Out?

-Freshly cooked poultry, meat, and game

-Cooked eggs

-Fresh produce excluding avocado, eggplant, spinach, tomatoes

-Dairy substitutes like coconut or almond milk

-Extra virgin olive oil and virgin coconut oil

-Herbal teas

-Certified gluten-free rice, quinoa, buckwheat, and amaranth

Adhering to such a limited diet is not easy. I get that. But look at a low histamine diet as part of an investigative process.  In the meanwhile, taking DAO enzymes may help immensely.  There are actually not all that many available on the market but one that I do know is pure and good is NutriCology DAO Histamine Digester. Additional support with probiotics ( Klaire Pro5 or Therbiotic Plus) and Immune support from Sinus Defense and Phospholipid Colostrum by Allergy Research Group is also extremely helpful.

We love hearing from you! Please comment below or email us at newsletter@sinusitiswellness.com.