What Does Histamine Do?

Medically Reviewed By Marc Meth, MD, FACAAI, FAAAI
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Histamine is a chemical produced by your immune system that can start a chain reaction to defend against allergens. When histamine is released, blood flow to the affected area of the body increases, causing an inflammatory cascade. Other immune system chemicals complete the chain reaction to repair the damage to your tissues. When your body produces too much histamine or is unable to break it down, it can cause symptoms such as difficulty breathing, sneezing, itching, and hives.

Read on to learn more about histamine and its effects on the body.

How does histamine work?

A hand taking a tissue
Javier Díez/Stocksy United

Histamine is one of the chemicals involved in defending the body against allergens. Mast cells and basophils produce most of the histamine in your immune system.

Mast cells are a type of white blood cell found in your body’s connective tissues. During an immune system response, they release chemicals that can create new blood vessels and widen existing ones.

Basophils are another type of white blood cell that release histamine from granules attached to them.

When your immune system encounters an allergen, it signals your mast cells to release histamine. Histamine increases blood flow to the affected area by widening your blood vessels, promoting inflammation. The increased blood flow allows other substances from your immune system to travel to the affected area and repair your tissues.

How do histamine receptors affect the body?

When histamine releases into the body, it binds to proteins called histamine receptors. The binding process will affect the body differently depending on where histamine is released.

There are four types of histamine receptors:

Histamine receptors Function
H1These receptors appear in many areas of the body, including your blood vessels, neurons, and smooth muscle cells in your airways. When they are activated, they can cause itchiness, pain, flushing, and difficulty breathing. H1 receptors also affect your emotions, learning, memory, and sleep-wake cycles.
H2These receptors are mainly located in your heart, stomach, and smooth muscle cells. They can cause an increase in stomach acid, headache, and rapid heartbeat when activated.
H3These receptors are primarily located in your central nervous system. They can affect histamine production and release.
H4These receptors are located in your bone marrow and blood. They regulate the release of white blood cells from your bone marrow and can affect mast cell function.

How do low levels of histamine affect the body?

H1 receptors play a role in your sleep-wake cycles, so having low levels of histamine can make you sleepy. Many antihistamine drugs cause drowsiness because they block these receptors.

Low histamine levels can also cause convulsions and seizures. Brain histamine levels are decreased in people with Alzheimer’s disease.

How do high levels of histamine affect the body?

When your body releases too much histamine or is unable to break it down, it can cause symptoms that we typically associate with allergic reactions, such as:

What can you do to counteract the effects of histamine?

There are certain things you can do to help counteract the effects of histamine. The two most common treatment methods are medications and dietary changes.


Antihistamines are drugs that treat conditions resulting from an excess release of histamine. These drugs can bind to your H1 and H2 receptors.

Antihistamines that bind to your H1 receptors can help alleviate symptoms of allergies and allergic rhinitis, or an allergic reaction that primarily affects the nose.

Doctors typically prescribe H2 antihistamines to treat conditions resulting from increased stomach acid production, like peptic ulcers and acid reflux.

While these medications usually come in tablet form, they can also be liquids, nasal sprays, creams, or eye drops.


The foods and drinks you consume can also contain histamine. A 2020 review of several studies suggests that sticking to a low histamine diet may help to alleviate the symptoms of high histamine levels, although more research is needed.

Foods that contain high quantities of histamine include:

  • shellfish
  • dried fruit
  • certain vegetables, such as spinach and avocados
  • smoked or processed fish and meat
  • fermented foods, like soy sauce and sauerkraut
  • certain dairy products, like aged cheese and yogurt

Some foods and drinks can trigger the release of histamine in the body even though they do not contain histamine themselves. These include milk, wheat, and alcohol.

Low histamine foods can include:

  • fresh meat and fish
  • eggs
  • non-dairy foods and drinks, like almond milk
  • gluten-free grains
  • fresh fruits with low citrus levels, like apples or blueberries

Frequently asked questions

These are a few other commonly asked questions about histamine. The answers have been medically reviewed by Dr. Marc Meth.

What triggers histamine release?

Allergens and certain foods can cause histamine release. Common allergens include pollen, animal dander, and dust. Foods like nuts, shellfish, and dairy may also trigger a release of histamine.

How does histamine affect inflammation?

When histamine releases into the body, it can cause your blood vessels to dilate. This process increases blood flow to the area of your body affected by an allergen, causing inflammation.

What time of day is histamine highest?

According to researchers, histamine levels are highest during the night. Histamine levels tend to be lowest in the afternoon.


Histamine is a chemical that starts a chain reaction in your body to defend against allergens. When histamine is released, blood flow to the affected area of the body increases, promoting inflammation. The increased blood flow allows other substances, like white blood cells, to travel to the affected area and repair your tissues.

In some cases, your body can release excessive amounts of histamine or become unable to break it down. This can result in symptoms including flushing, hives, itchy skin, and difficulty breathing.

Symptoms resulting from high histamine levels can be treated with antihistamine medications.

Talk with your doctor if you are experiencing symptoms consistent with high histamine release.

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Medical Reviewer: Marc Meth, MD, FACAAI, FAAAI
Last Review Date: 2022 Jun 10
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