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What is Histamine?

Learn more about histamine and histamine intolerance, including how to manage histamine symptoms and the treatment options available here.

Histamine: What It Is and What It Does

Histamine is a substance that your cells produce to help your immune system respond to allergy triggers1. It’s mostly recognised for its role in causing allergy symptoms. For example, histamine can cause you to sneeze, feel itchy, or make your eyes tear up. But it also plays a key role in additional tasks, such as regulating your sleeping and waking cycle and cognitive function.

Read on to learn more about histamine, what it does, and how to deal with it in our dedicated guide. In this guide:

  • What is histamine?
  • Histamine intolerance symptoms
  • What can trigger histamines?
  • How to clear histamine from your body
  • Histamine FAQs

What is histamine?

Histamine is an amine that is involved in immune responses throughout your body. Amines are made of nitrogen atoms bound with other atoms. These can bond to other cells throughout your body to respond to injury or allergy triggers.

What does histamine do?

Histamines play an important role in how your body responds to allergies. Essentially, their job is to help rid your body of something that’s bothering you, such as an allergy trigger, or ‘allergen’.

Most allergy triggers, such as pollen and pet dander, can often seem harmless, but your immune system can see them as a threat. As a result, it can overreact and release histamine to help keep your body safe. This can result in those familiar allergy symptoms, such as itching and sneezing. That’s why people often use antihistamines to treat their symptoms.

Histamine intolerance symptoms

Sometimes people can have high levels of histamine in their body, which can result in histamine intolerance. This can happen if your body can’t break down histamine like it’s supposed to. This excess build-up of histamine can result in a range of symptoms such as:

  • Headaches

  • Migraines

  • Fatigue

  • Nasal congestion

  • Digestive problems

  • Irregular periods

  • Skin symptoms, such as hives or itchy skin

  • Dizziness

  • Anxiety

  • Abdominal pain, bloating and diarrhoea

  • High blood pressure

  • Changes to heart rate

What can trigger histamines?

Histamines can be triggered by allergens. Common allergens include:

  • Pollen (hay fever)

  • Dust mites

  • Pet dander

  • Certain types of foods, such as peanuts, milk and eggs

Other common histamine triggers include:

  • Dust

  • Air pollution

  • Airborne chemicals, such as artificial fragrances

  • Eating large meals

  • Dehydration

What conditions involve histamine?*

Histamine plays a central role in several allergic conditions, including:

  • Atopic dermatitis – also known as eczema

  • Contact dermatitis – can occur when your body encounters fragrances, metals, and preservatives

  • Allergic rhinitis – also known as hay fever, this can happen because of pollen, dust, mould etc.

  • Allergic asthma – can be triggered by all of the above.

  • Allergic conjunctivitis – can occur when the conjunctiva of your eyes gets swollen or inflamed because of allergens

How to clear histamine from your body

There are various ways you can help keep your histamine levels in check:

Antihistamines

Antihistamines, such as BENADRYL® Allergy Relief, can help treat allergy symptoms caused by triggers such as pollen and pet dander. BENADRYL® Allergy Relief can be taken as required up to three times per day.

Corticosteroids

Corticosteroids can help with inflammatory allergy and histamine effects. For example, topical corticosteroids can be used to reduce inflammation and irritation caused by conditions such as contact dermatitis and eczema.

Histamine FAQs

Certain types of medications for blood pressure and depression can affect how diamine oxidase (the enzyme that breaks down histamine) is produced. When your body doesn’t break down histamine as it should, this can lead to histamine intolerance, which can cause high levels of histamine to build up in your body.

Histamines are chemicals produced by your immune system to protect your body from something that is bothering it, such as allergens. They can cause allergy symptoms, such as sneezing and itching. Antihistamines, on the other hand, are medicines that help to manage allergy symptoms.

Certain types of food are naturally high in histamines, such as cured meat, cheese, and canned fish. Other types of food don’t contain much histamine but can trigger your white blood cells to make it. These can include bananas, pineapples, and citrus fruits.

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BENADRYL® Allergy One A Day Tablets contain cetirizine (12+ years). BENADRYL® Allergy Children’s 1mg/ml Oral Solution contains cetirizine (2+ years). BENADRYL® Allergy Children’s 6+ 1mg/ml Oral Solution contains cetirizine. BENADRYL® Allergy Relief (12-65 years) contains acrivastine. BENADRYL® Allergy Relief Plus Decongestant Capsules (12-65 years). BENACORT® 64 micrograms Nasal Spray contains budesonide. For prevention and treatment of hayfever (18+ years). BENACORT® Hayfever Relief for Adults 64 micrograms Nasal Spray contains budesonide (18+ years). BENADRYL® Allergy Natural Relief Nasal Spray (from birth) is a medical device.

Always read the label. Ask your pharmacist for advice.

© Kenvue UK Limited, 2025. This site is published by Kenvue UK Limited which is solely responsible for its contents. It is intended for a UK audience. BENADRYL® is a registered trademark.

Last updated on: April 2025.

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