Do you experience unexplained headaches or anxiety? What about irregular menstrual cycles or gastrointestinal disorders? Do you get an itchy tongue or runny nose when you eat bananas, avocados, or eggplant? If you answered “yes” to any of these questions, then you could have histamine intolerance.

Histamine intolerance can be extremely frustrating because your symptoms often feel like they come out of the blue. Trust me when I say, I understand! I had histamine intolerance for several years before I discovered the root cause. I kept getting terrible headaches at the most seemingly unpredictable moments. Fortunately, I discovered that histamine intolerance was the source of this frustrating symptom.

In this article, I’ll walk you through all there is to know about histamine intolerance and how to combat it. First, let’s discuss what having a histamine intolerance means.

What is Histamine Intolerance?

Let’s back up for a second and cover the basics of what histamine is and what an intolerance may feel like for you. 

What is Histamine?

Histamine is a chemical involved in your immune system, digestion, and central nervous system. As a neurotransmitter, it communicates important messages from your body to your brain. It is also a trigger for the production of stomach acid, which helps you break down and digest food effectively.

You might be familiar with histamine in relation to your immune system. If you’ve ever reached for ZYRTEC® or Benadryl® to provide quick relief from your seasonal or food allergy symptoms, then you’ve likely experienced a histamine reaction.

Histamine’s main job is to signal an immediate inflammatory response within the body. It raises a red flag to move your immune system into action against potential attackers. As the name suggests, antihistamines work to prevent this response.

How Does Histamine Affect Your Body?

Histamine causes your blood vessels to swell so that your white blood cells can quickly move in to resolve any problems—it’s all part of your body’s natural immune response! Typically, enzymes will break down the histamine so that it doesn’t build up in your bloodstream. If histamine isn’t broken down properly or regularly, it builds up, and you may eventually develop a histamine intolerance.

As histamine travels throughout your bloodstream, it can affect your gut, lungs, skin, brain, and even your entire cardiovascular system. This chemical can contribute to a wide range of symptoms often making it hard to pinpoint this issue.

Symptoms of a Histamine Intolerance

Contrary to popular belief, histamine intolerance is not an allergic reaction. It becomes an issue when your histamine breakdown is impaired. This causes excess histamine to build up in your body, resulting in symptoms that appear similar to an allergic reaction or common seasonal allergies. Histamine intolerance is often difficult to pinpoint or diagnose due to the resemblance of common allergy symptoms. Histamine intolerance may cause symptoms such as:

• Abdominal cramps
• Abnormal menstrual cycle
• Arrhythmia, or accelerated heart rate
• Sleep disturbances
• Difficulty regulating body temperature
• Fatigue
• Flushing
• Headaches/migraines
• Hives
• Hypertension
• Mood disorders
• Nasal congestion, sneezing, difficulty breathing
• Nausea, vomiting
• Tissue swelling
• Vertigo or dizziness

Mood Disorders

The connection between histamine and stress can worsen mood disorders. In the brain, histamine acts as a neurotransmitter that can affect the levels of GABA, dopamine, and serotonin. This can lead to heightened feelings of anxiety and depression.

Sleep Disturbances

Histamine promotes wakefulness by inhibiting the neurons that promote sleep.¹ An excess of histamine can lead to insomnia, while improper synthesis of histamine can lead to excessive sleepiness.

Vertigo or Dizziness

When your body experiences a trigger to release histamine, it creates inflammation. Since histamine intolerance often mimics seasonal allergies, your inner ear can become inflamed by excess mucus production. This inflammation can make the inner ear irritated, leading to an imbalance in your equilibrium which can cause dizziness and vertigo.² 

How Does the Body Break Down Histamine?

Histamine intolerance results from an imbalance between the amount of histamine produced and your body’s ability to break it down and clear it out. Your cells release histamine in response to a trigger. Once formed, histamine is either stored or broken down by an enzyme. 

In the central nervous system, histamine is mainly broken down by histamine N-methyltransferase (HMT). In the digestive tract, histamine is broken down by diamine oxidase (DAO). These enzymes help your body naturally break down histamine and clear it out. ³

Due to a variety of reasons, your body might not produce enough of one or the other, or both enzymes. HMT is produced inside the cells and is usually more genetically influenced. DAO is produced in the intestine and is responsible for the breakdown of ingested histamine. If there has been intestinal damage, DAO production might be reduced.

What else could cause low DAO? 

• Gluten intolerance
• Leaky gut
• SIBO
• DAO-blocking foods: alcohol, energy drinks, and tea
• Genetic mutations (common in people of Asian descent)
• Inflammation from Crohn’s, ulcerative colitis, and inflammatory bowel disease.
• Medications can inactivate DAO including:
  • Non-steroidal anti-inflammatory drugs (ibuprofen, aspirin)
  • Antidepressants (Cymbalta, Effexor, Prozac, Zoloft)
  • Immune modulators (Humira, Enbrel, Plaquenil)
  • Antiarrhythmics (propanolol, metoprolol, Cardizem, Norvasc)
  • Antihistamines (Allegra, Zyrtec, Benadryl) 
  • Histamine (H2) blockers (Tagamet, Pepcid, Zantac)

What Causes High Histamine Levels?

We naturally produce histamine along with DAO. However, when outside factors interfere with how HMT and DAO work, their presence in your gut can decrease. Low levels of HMT or DAO enzymes mean histamine can be produced without regulation.⁴ Outside factors contributing to the overproduction of histamine include:

• Allergies (IgE reactions)
• SIBO 
• GI bleeding/damage
• Leaky Gut
• Mast-Cell Activation 
• Histamine-rich foods

Mast Cell Activation

Mast cell activation may be a primary cause of histamine intolerance, however, it may not be the cause for everyone. Mast cells can be found in your digestive tract, urinary tract, reproductive organs, respiratory tract, and skin cells. These cells store inflammatory mediators that induce histamine. 

When your body is posed with a threat such as an allergic reaction, infection, or environmental toxins, your mast cells are activated, releasing histamine.⁵ This triggers an inflammatory response in your body, often mimicking allergy symptoms. Environmental exposures that could induce mast cell activation include mold, allergens, viruses, chemicals, and heavy metals. 

Foods to Avoid if You Have Histamine Intolerance

Many foods naturally contain histamine, trigger a release of histamine, or block the enzyme DAO.⁶ I recommend avoiding the following foods until you have addressed the underlying cause of your histamine intolerance.

Histamine-Rich Foods

Your diet should consist of foods with moderate to low levels of histamine. The high histamine foods list includes:

• Aged cheeses, including goat cheese
• Cured meats: bacon, salami, pepperoni, luncheon meats, and hot dogs
• Dried fruit: apricots, prunes, dates, figs, raisins
• Fermented alcoholic beverages, especially wine, champagne, and beer
• Fermented foods: sauerkraut, vinegar, soy sauce, kefir, yogurt, kombucha, etc.
• Most citrus fruits
• Nuts: walnuts, cashews
• Peanuts
• Soured foods: sour cream, sour milk, buttermilk, soured bread, etc.
• Smoked fish and certain species of fish, including mackerel, mahi-mahi, tuna, anchovies, sardines
• Fruits: avocados and tomatoes
• Vegetables: eggplant and spinach
• Vinegar-containing foods: pickles, mayonnaise, olives

Histamine-Releasing Foods

While not histamine-rich, some foods can trigger your cells to release histamine, causing symptoms. Histamine-releasing foods include:

• Alcohol
• Artificial preservatives and dyes
• Bananas
• Chocolate
• Food containing dairy (cow’s milk)
• Nuts
• Papaya
• Pineapple
• Shellfish
• Strawberries
• Tomatoes
• Wheat germ

DAO-Blocking Foods

Some foods and drinks interfere with your body’s natural balance of HMT and DAO enzymes. As you continue to consume these foods, the less your DAO enzymes will be able to keep your histamine intolerance symptoms in check. DAO-blocking foods to avoid while following a histamine intolerance diet include:

• Alcohol
• Black tea
• Energy drinks
• Green tea
• Mate tea

Foods to Enjoy if You Have Histamine Intolerance

That was a long list! You might be wondering what on earth you CAN eat if you have histamine intolerance. Fortunately, you can enjoy plenty of foods on a low-histamine diet. Remember, freshness is key when you have histamine intolerance and follow a histamine-free diet.

Low-Histamine Foods

• Cooked eggs
• Cooking oils: olive oil, coconut oil
• Dairy substitutes: coconut milk, rice milk, hemp milk, almond milk*
• Fresh fruits: mango, pear, watermelon, apple, kiwi, cantaloupe, grapes
• Fresh vegetables (except tomatoes, spinach, and eggplant)
• Freshly caught fish
• Freshly cooked meat or poultry
• Gluten-free grains*: rice, quinoa, corn, millet, amaranth, teff
• Herbal teas
• Leafy herbs
• Pure peanut butter*

Following a low-histamine diet is one of the best things you can do to manage your histamine intolerance. It’s important to avoid grains, legumes, and nuts until you can successfully reintroduce them to your diet. While a low histamine diet can feel strict, it will be worth it for symptom management and relief. 

Elimination/Reintroduction

For optimal results, remove high histamine foods for 30 days. Then, reintroduce them one at a time by following my elimination diet guidelines.

How to Test for Histamine Intolerance

The Histamine Blood Test

To determine a diagnosis of histamine intolerance, I recommend a histamine blood test through Dunwoody Labs. This blood test checks for histamine and DAO enzyme ratio levels. A high ratio of histamine to DAO signifies that your DAO levels are too low to break down the histamine.

Measuring Lipopolysaccharide

A study conducted found a correlation between histamine H1 receptors (H1R) and lipopolysaccharide (LPS) production, suggesting a link between immune response and histamine signaling.⁷ The higher the level of lipopolysaccharide, the higher the indication of an inflammatory response. Measuring lipopolysaccharide levels could help indicate possible inflammation and a connection to histamine intolerance. 

Trial of DAO

If you cannot get your blood tested, starting a histamine intolerance diet is the next best solution. With each meal, add a DAO supplement (see more on this below). If your symptoms resolve, this may indicate low DAO levels.

Food Journal

It can be difficult to determine which foods are leading to your symptoms. I recommend keeping a food journal to record everything you eat each day as well as your health symptoms. This will help you pinpoint which foods and ingredients may trigger a histamine intolerance. 

How to Treat Histamine Intolerance?

After years of working with patients in my clinic, I found simple actions that anyone can take to address histamine intolerance symptoms. 

Ease Your Symptoms Through Diet and Supplements

If you’ve regularly reached for antihistamines or H2 antagonists such as ZYRTEC® or Benadryl® to treat your symptoms of histamine intolerance, you could be doing your gut more harm. Antihistamines block stomach acid production which leads to low stomach acid levels. This can result in symptoms of acid reflux. 

If you’ve experienced this from taking antihistamines, check out my latest product, Gut Restore with Betaine and HCL. This formula promotes optimal stomach acid levels. By increasing acid levels, your body can break down food and absorb nutrients more efficiently. In addition, it helps to kill off harmful bacteria in your stomach before having a chance to enter your digestive tract.

To address the root cause of histamine intolerance, you must first minimize dietary histamine. Do this by eating a low-histamine diet and avoiding foods that block DAO. I also recommend taking a DAO supplement such as Histazyme for immediate relief. I’ve had many success stories from my patients telling me how relieved they feel not having to worry about histamine intolerance when eating out.

When battling histamine intolerance, this supplement was a lifesaver for me. I wouldn’t have a meal without it! One or two capsules no more than 15 minutes before you eat will help your body respond to symptoms.

Address the Root Cause of Your Histamine Intolerance

The key to overcoming symptoms is to identify the root cause of the issue. I have found that histamine intolerance is often caused by a gut health issue, particularly Small Intestinal Bacterial Overgrowth (SIBO).⁸ In fact, SIBO was the culprit of my histamine intolerance. Other common contributors include Candida overgrowth, Leaky Gut, and gluten intolerance.

If you think a gut infection is causing your body’s histamine intolerance, I recommend completing my Leaky Gut Breakthrough® Program. It includes diagnostic quizzes, meal plans, supplement recommendations, and handy tools that equip you to address your gut health symptoms, all from the comfort of your home.

The Final Word

Living with the symptoms of histamine intolerance can be tricky when they’re often confused with seasonal allergies. These mysterious symptoms can be severe, and often leave you frustrated and even debilitated. The good news is that you can now find immediate relief with my DAO supplement, Histazyme. If you’re experiencing severe symptoms paired with gut health issues, I recommend following my Leaky Gut Breakthrough® Program to address the root cause and begin to take back your life—for good!

Additional Resources

For more information, check out my interview with Kara Fitzgerald, ND, where we discuss the overlap between allergic diseases and autoimmunity and how our exposure to medications and environmental toxins plays a part.