Histamine Definition: What Histamine Does and How It Causes Allergies


What is a histamine release?

Histamine release refers to the process by which histamine, a chemical compound produced by the body's immune system, is released from cells into the bloodstream or surrounding tissues. This release can occur as a result of an allergic reaction, certain medications, or other triggers.

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What Are Histamines?

Histamines are molecules produced by certain cells in the body, such as mast cells, that play an important role in the immune system response. When you encounter an allergen or a foreign substance, these cells release histamines into the bloodstream to get rid of the substance.

The way histamines do this is by binding to receptors in various tissues throughout our body, causing inflammation and a range of reactions such as itching, sneezing, and increased mucus production. These reactions are supposed to help get the substance out of your body through whatever means necessary, thus protecting you and your health.

While histamines are a vital part of our immune system response, they can also cause problems for people who are sensitive to them. For example, people with allergies may have an overactive immune response, releasing histamines in response to harmless substances such as pollen or pet dander. This can lead to symptoms such as sneezing, runny nose, and itchy eyes. In addition, histamines are also involved in certain types of headaches, such as migraines, and can cause symptoms such as flushing and hives.

How Does Histamine Cause Allergies?

When an allergen enters the body, the immune system recognizes it as a threat and releases histamines. These histamines bind to specific receptors on various cells. This causes blood vessels to dilate and become more permeable, resulting in symptoms such as redness, swelling, and itching.

What is Histamine Intolerance?

Histamine intolerance is a condition that occurs when the body is unable to properly break down the chemical histamine. In most cases, this intolerance is caused by insufficient production of the enzyme diamine oxidase (DAO) and histamine-N-methyltransferase, which are responsible for breaking down histamines in the body.

Histamine intolerance can be easily confused with an allergy, although the two have some distinct differences. While allergens trigger IgE antibodies, histamine intolerance occurs when too much histamine is circulating inside the body in response to foods. Therefore it is more related to a high-histamine diet than an actual allergic reaction.

What Causes High Levels of Histamine?

Several conditions and activities can contribute to abnormally high histamine levels. They can range from certain autoimmune diseases to the ingestion of certain foods. Let’s go into more depth about each of the different reasons from the list below.


Histamine is released in response to an allergen, such as pollen, mold, dust mites, or pet dander. In people with allergies, the immune system overreacts to these harmless substances and releases more histamine than necessary. This then causes all too familiar symptoms such as sneezing, swelling, watery eyes, and more.

Genetic Deficiency in DAO Production

Some people have a genetic variation that results in reduced DAO production or activity, which impairs their ability to break down histamine in the digestive tract. This can lead to an accumulation of histamine in the body, causing symptoms such as headaches, flushing, itching, and digestive issues. This condition is known as histamine intolerance or histaminosis.

Consuming Foods High in Histamine

Histamine occurs naturally in many foods, especially those aged, fermented, or preserved. When consumed, histamine can be absorbed into the bloodstream and cause symptoms in sensitive people. High-histamine foods include aged cheeses, cured meats, fermented foods such as kimchi and sauerkraut, and certain types of fish (such as tuna, mackerel, and sardines).

Histamine-Releasing Foods

In addition to consuming foods that are high in histamine, some people may also be sensitive to foods that trigger the release of histamine in the body. These foods do not necessarily contain histamine themselves but rather stimulate the body to release histamine as part of an immune response. Examples include alcohol, tomatoes, strawberries, and citrus fruits.


Some medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can block the production of an enzyme called diamine oxidase (DAO), which is responsible for breaking down histamine in the gut. This can lead to an excess of histamine in the body.

Chronic Inflammation

Chronic inflammation can also lead to high histamine levels, as the body may release histamine as part of the immune response. This can occur in conditions like autoimmune diseases, allergies, and chronic infections.

Mast Cell Activation Syndrome (MCAS)

MCAS is a medical condition that involves the inappropriate activation of mast cells, which are immune cells that play a role in the release of histamine. This can lead to high histamine levels and a range of symptoms, including flushing, itching, gastrointestinal issues, and fatigue. A variety of factors, including infections, stress, and environmental triggers can trigger MCAS.

Gut Dysbiosis

The gut microbiome plays an important role in histamine metabolism. Imbalances in the gut microbiome can lead to high histamine levels. This can occur in conditions like small intestinal bacterial overgrowth (SIBO) and inflammatory bowel disease (IBD), which can disrupt the balance of gut bacteria and impair DAO function.

Hormonal Imbalances

Hormonal imbalances can also play a role in histamine metabolism. Estrogen has been shown to increase DAO activity while progesterone has been shown to decrease it. Fluctuations in hormone levels during the menstrual cycle or menopause can therefore affect histamine levels and trigger symptoms in people sensitive to histamine.

Other Medical Conditions

In addition to MCAS, gut dysbiosis, and hormonal imbalances, several other medical conditions can also contribute to high histamine levels. These include:

  • Histamine intolerance or histaminosis
  • Autoimmune diseases such as rheumatoid arthritis, lupus, and multiple sclerosis
  • Chronic infections such as Lyme disease, viral infections like hepatitis and HIV, and bacterial infections like tuberculosis
  • Gastrointestinal disorders like celiac disease, Crohn's disease, and ulcerative colitis

Symptoms of Histamine Intolerance

Histamine intolerance symptoms can be wide-ranging and can vary from person to person. Some common symptoms include:

  • Headaches or migraines
  • Flushing or hives
  • Itching or eczema
  • Abdominal pain or bloating
  • Diarrhea or constipation
  • Nausea or vomiting
  • Irregular menstrual cycle or painful periods
  • Fatigue or difficulty sleeping
  • Anxiety or irritability
  • Heart palpitations or rapid heartbeat

When to See a Doctor for Histamine Intolerance

If you are experiencing histamine intolerance symptoms, here are some signs that you may need to see a doctor:

  • You are experiencing persistent or worsening symptoms, despite making dietary changes or other lifestyle modifications.
  • Your symptoms are interfering with your daily activities or quality of life.
  • You are taking medications that may be contributing to your symptoms, such as certain antidepressants or blood pressure medications.
  • You have other medical conditions that may be contributing to your symptoms, such as gastrointestinal disorders or chronic infections.

When to See a Doctor for Allergies that Trigger Histamine

If you have allergies that trigger the release of histamine, it's important to work with a healthcare provider to identify the allergen and develop an appropriate treatment plan. Here are some signs that you may need to see a doctor for allergies:

  • You are experiencing severe or life-threatening symptoms, such as difficulty breathing or swelling of the throat.
  • Your symptoms are interfering with your daily activities or quality of life.
  • You are unsure of the cause of your symptoms or are having trouble identifying the allergen.
  • You are taking medications or have other medical conditions that may be interacting with your allergies or contributing to your symptoms.
  • You have a history of severe allergic reactions, such as anaphylaxis.


When you go to see your doctor with symptoms that suggest histamine intolerance, they'll start by asking about your medical history, diet, and symptoms. They may also perform a physical exam to check for signs of an allergic reaction, like hives or skin rashes. Here are several tests and assessments they might do to help identify the underlying cause of your symptoms.

Elimination diet

With the elimination diet, the doctor will ask you to remove high-histamine foods from your diet for a certain period of time. Once the period is over, your doctor will have you reintroduce those same foods back into your diet to see if you experience any reactions or symptoms as a result.

Blood and Urine Tests

Some doctors may measure the levels of histamine and other related compounds in the blood to help diagnose histamine intolerance. Urine tests may also help measure histamine levels and other compounds that may indicate histamine intolerance.

Laboratory Tests

Your doctor may recommend laboratory tests, such as the diamine oxidase (DAO) test, which measures the levels of DAO in your blood. The other test is the histamine release test, which measures the release of histamine from immune cells in response to certain stimuli.

At-Home Allergy Tests

At-home allergy tests, such as the allergy test from Wyndly, are also available. The Wyndly at-home allergy test is a blood test that screens for IgE antibodies to seasonal and environmental allergens. At-home allergy tests are a convenient and easy method of identifying what you are allergic to which is important for finding a treatment plan that works for your allergies.


Histamine intolerance treatment options can vary depending on the severity of the condition, the underlying causes, and individual preferences. Here are some commonly recommended treatment options:

Eating a Low Histamine Diet

One of the most effective ways to manage histamine intolerance is to avoid foods that are high in histamine or that trigger histamine release. A low-histamine diet may involve eliminating foods like aged cheese, fermented foods, citrus fruits, and certain types of meat and fish. Low histamine foods can include fresh fruits such as apples, fresh meat and fish, and non-dairy foods and drinks.


Some people may benefit from supplements that help support histamine metabolism and reduce inflammation, such as Vitamin C, quercetin, and DAO (diamine oxidase). Your healthcare provider may also recommend natural antihistamines such as Vitamin B6, and copper. It is important to talk to your doctor before adding supplements to your diet.


Antihistamines and other medications that help to reduce inflammation and improve digestive function may be prescribed to manage symptoms of histamine intolerance. Some of these can be found over the counter. However, if over-the-counter medications aren’t working for you, speak to your doctor about prescribed medications that can help.

Sublingual immunotherapy (SLIT)

If you have seasonal or environmental allergies, allergy immunotherapy can retrain your immune system to stop reacting to your triggers. Sublingual immunotherapy is a type of allergy treatment that involves placing allergen extracts under the tongue to gradually desensitize the immune system. This decreases allergy symptoms and can provide long-term allergy relief.

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