Histamine Intolerance: Signs, Causes & Treatment

What is Histamine?

Histamine is a chemical the body produces naturally and it is responsible for some major functions. It is present in the blood cells, but it is also a natural component in many different foods. It works as a neurotransmitter in the central nervous system to communicate messages to the brain and assist pituitary hormone secretion, cognitive functions and appetite suppression.

In addition, it is an essential part of the immune system and digestive system, as it triggers stomach acids to break down food in the stomach (x). Its roles are vital to life. However, if levels get too high or if the body cannot break it down properly, it can affect normal bodily functions.

What is Histamine Intolerance?

This occurs from a disequilibrium that causes the chemical to accumulate in the body. Normally, there are two main enzymes in the body that metabolize the chemical, N-methyltransferase (HNMT) and diamine oxidase (DAO) (x, x). HNMT metabolizes histamine in the central nervous system. In contrast, DAO breaks it down in food to help maintain balance in the body. However, sometimes DAO is unable to break it down. This is the most common reason that the body accumulates excess histamine, which leads to histamine intolerance and the unpleasant symptoms that may manifest (x).

Signs of Histamine Intolerance

Histamine intolerance is not a true allergy, but the symptoms it causes may be similar to an allergic reaction. Although they are not usually life-threatening, some of the symptoms can be severe (x). For example, it may cause:

Patients may also experience headaches, migraines, dizziness, fatigue or insomnia. Histamine intolerance may also cause changes in mood and make the patient more irritable. The intolerance may also trigger chest pain, rapid heartbeat and unexplained anxiety. It can also cause hypotension or hypertension and the patient may notice swelling around the eyes, throat or lips (x).

Causes of Histamine Intolerance

There are several factors that may result in histamine intolerance. It may result from DAO blockage and bacterial overgrowth. The body may also overproduce the chemical or have an inability to break it down properly. 

DAO Blocking

There are a number of reasons for DAO blocking from both internal and external triggers (x). For example, some individuals may have low DAO levels from eating histamine-rich foods. These foods contain microbial fermentation that can convert the amino acid histidine to histamine. Some prescription and over-the-counter medications can also block DAO production. Gut flora imbalance can cause bacteria overgrowth in the gut, which can increase histamine levels. Gut health issues such as gastrointestinal disease can also reduce DAO.


Mast cells are responsible for producing histamine and if these cells are overactive, levels increase. This condition is called mastocytosis and mast cells may accumulate abnormally in the skin and other parts of the body. Mastocytosis is not very common, but it can interfere with body functions (x).

Bacterial Imbalance

Small intestinal bacterial overgrowth (SIBO) is a condition in which bacteria grows excessively in the small intestine. It causes chronic diarrhea, malabsorption and unintentional weight loss. Patients can also develop nutritional deficiencies and osteoporosis (x). If there are too many bacteria producing it or not enough bacteria that degrade it, it may lead to excess histamine production (x). Bacteria may become imbalanced from undigested food. DAO cannot break down the excess histamine, which is why patients with allergies may also suffer from a variety of digestive health issues.


Genetic mutations may interfere with DAO and histamine N-methyltransferase enzymes that help bind and break down histamine to avoid excess. But if genetic changes decrease DAO levels, it keeps the body from breaking down histamine (x).

Gastrointestinal Disorders

Different gastrointestinal conditions may often result in histamine intolerance. For example, Crohn’s disease, irritable bowel syndrome (IBS), gluten sensitivity, leaky gut syndrome, small intestine bacterial overgrowth (SIBO) and ulcerative colitis may disrupt histamine metabolism in the body (x).

UV Light

Interesting new research suggests that UV light may trigger additional histamine. In fact, studies reveal that some phenothiazine compounds may stimulate the reaction. These compounds are present in prescription drugs for conditions that range from anxiety to depression. Still, there are numerous over-the-counter and prescription drugs that affect DAO levels directly or indirectly (x).


Patients who take certain prescription or over-the-counter medications may notice recurring allergy-like symptoms. It may be a good idea to get tested for histamine intolerance. Some antidepressants, muscle relaxants, non-steroidal anti-inflammatory drugs (NSAIDs), heart medications and antipsychotics may increase the risk (x).

Adrenal Fatigue

Adrenal fatigue develops from prolonged exposure to stress and patients may experience cortisol production imbalances throughout the day. Likewise, it may increase histamine production because of inflammation that triggers the chemical as a defense mechanism (x).

Causes of Histamine Intolerance

What Role Does Diet Play?

Many scholars link histamine with the body’s immune responses. However, different foods and drinks contain different levels of histamine that increase as the food ferments, ages or spoils. There are also foods and drinks that contain compounds that hinder DAO and HNMT enzyme function. Researchers are still trying to determine the exact levels in food and how some nutrients may hinder DAO and HNMT activity.

Current research shows that alcohol, fermented foods (kefir, kombucha, sauerkraut, yogurt, soy sauce), dairy, shellfish and foods that contain yeast may contain high histamine levels or trigger its release. Citrus fruits, dried fruit, eggplants, avocados and spinach may also contain large amounts of histamine (x). Similarly, some foods may also block DAO function specifically such as alcohol, black tea, energy drinks and raw egg whites.

Treating Histamine Intolerance

Dietary Changes

A large part of managing and treating histamine intolerance is avoiding factors that may trigger the symptoms. One of the most important management tools is making dietary changes and making conscious dietary choices.

Elimination Diet

This intervention is usually the first line of treatment for many patients. The elimination diet forces patients to avoid all foods high in histamine, foods that cause its release and those that block DAO for about one to three months. Next, physicians monitor the patient’s symptoms and assess how the body reacts (x).

Low Protein Diet

Histamines are made from amino acids derived from proteins. Bacteria and yeast turn the amino acid histidine into histamine, so protein can elevate histamine levels in the body. This is a normal process, but if patients have a histamine intolerance it can cause symptoms (x).

Medication & DAO Supplements

Aside from dietary changes, patients with histamine intolerance may also benefit from some medical treatments, depending on what causes the condition or the symptoms. In a small study, researchers used a small sample size of 14 participants and concluded that 13 of them experienced a decrease in symptoms after a daily dose of DAO supplement for about two weeks (x). Corticosteroids and antihistamine medications are common forms of treatment.

Patients can also try DAO supplements to manage the intolerance. However, the supplements will not cure the condition. But it can help metabolize what the patient consumes from food (x).


In many cases, patients with histamine intolerance may also suffer from damage to the digestive lining or excess bacteria that metabolize it (x) . Therefore, the key step here is to rebalance the gut flora. Research states that probiotics may be an effective way to prevent and treat food allergies and food intolerances (x).

Supplements for Histamine Intolerance

Ginger Root

As a rhizome, ginger root may be able to help deter allergic reactions. Apart from that, patients may also use it as an H2 inhibitor (x). It also has antioxidants and bioactive compounds that may help reduce inflammation in the body. Research states that ginger may also help support the digestive system, relieving nausea and vomiting. As a dietary supplement, the recommended dosage for ginger root extract powder is 1,000 mg once a day. Consult a doctor before taking this supplement. It may also cause heartburn, so take it with at least 8 oz. of water.


Mangosteen may have effective healing powers thanks to its high antioxidant content. Since histamine intolerance can also develop from bacterial overgrowth, mangosteen’s antibacterial and anti-inflammatory properties may help combat different forms of yeast and bacteria in the body. Similarly, it may simultaneously reduce inflammation from allergies and bacterial overgrowth. In addition, various scientific studies note that mangosteen may be able to help reverse histamine-type allergic reactions in the body (x, x). The suggested serving size for mangosteen extract powder is 3,000 to 6,000 mg a day, or following a physician’s instructions.

Vitamin C

Vitamin C can function as a natural antihistamine and boost the immune system. It is one of the most common immune-stimulating tools and patients often use it to prevent or treat the common cold and flu. It is a powerful antioxidant that can help protect the body from oxidative damage. According to studies, intravenous doses may also help treat allergic diseases and manage allergic reactions (x). As a dietary supplement, take 1,000 mg of vitamin C/ascorbic acid powder per day, if a doctor approves the dosage.


Butterbur is a plant extract that originates in Europe, Asia and some parts of North America and over the years, people used it to treat allergic rhinitis, or seasonal allergies. The National Center for Complementary and Integrative Healing (NCCIH) suggests that butterbur may have antihistamine properties (x). The recommended dosage for butterbur extract powder is 150 mg a day with water, after consulting a physician.


Quercetin is a natural antioxidant flavonoid compound in many foods and herbs, such as apples, broccoli, green tea, parsley, turmeric and red onions. According to research, quercetin supplementation may have anti-allergic and antihistamine effects (x). As a dietary supplement, the recommended serving size for quercetin dihydrate powder is between 250 and 500 mg once or twice a day. Consult a doctor before taking this supplement.

Bottom Line

Histamine intolerance develops from a disequilibrium in histamine metabolism that causes the chemical to build up in the body. Histamine is a natural component in food that plays an important role in the central nervous system for communicating messages to the brain. It is also an important factor in immune defense. Symptoms of intolerance often mimic an allergic reaction, causing headaches, runny nose, itching and hives. 

There are several different factors that may cause intolerance. Usually histamine intolerance results from genetics, gastrointestinal disorders, bacteria overgrowth, UV lights and adrenal fatigue. These factors can cause histamine to accumulate in excess or interfere with its metabolism.

However, patients can also manage the condition by taking steps to avoid the triggers. Physicians may recommend an elimination or low-protein diet to avoid histamine-rich foods or take medication or probiotics to balance bacteria in the digestive system. There are also supplements that may help. However, supplements are not a proper medical treatment for histamine intolerance or any other condition. Instead, they aim to benefit overall health. Consult a doctor before taking any supplements.

Author: James D