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What is Histamine Intolerance?

histamine intolerance

Histamine is an important chemical that’s responsible for several functions in the body; it is one of the main substances released during an immune reaction. Histamine intolerance refers to the buildup of histamine inside the body, which can cause a variety of signs and symptoms.

Causes of histamine intolerance

Normally, the body breaks down ingested histamine, using an enzyme called diamine oxidase (DAO). Once histamine is inside the cell, another enzyme known as histamine-N-methyltransferase (HNMT) will break it down. Any condition that alters the activity of these two enzymes can lead to a buildup of histamine inside the bloodstream, and eventually, histamine intolerance.

Here is a shortlist of some causes:

Drugs that decrease DAO and/or HNMT levels

  • Theophylline
  • Antibiotics
  • Heart medications
  • Painkillers
  • Diuretics
  • Tuberculosis drugs
  • Non-Steroidal Anti-Inflammatory Drugs (e.g. aspirin, diclofenac)

Other factors

  • Alcohol
  • Inflammatory bowel disease
  • Vitamin B6 deficiency
  • Physical trauma
  • Extreme temperatures

Some dietary choices have also been documented to cause histamine intolerance (e.g. chocolate, yogurt, green tea). For a more comprehensive list, take a look at this article.

Symptoms of histamine intolerance

The frequency and severity of symptoms vary greatly from one patient to another; however, the typical clinical presentation tends to be similar to that seen during an allergic reaction. Signs and symptoms may include:

  • Flushing
  • Runny nose
  • Itchy eyes
  • Sneezing
  • Dyspnea (shortness of breath)
  • Hives
  • Very itchy skin
  • Abdominal pain
  • Chronic constipation
  • Digestive symptoms (e.g. Nausea, vomiting, bloating, gas)
  • Lethargy (severe exhaustion)
  • Dizziness
  • Eczema
  • Tachycardia (high pulse)
  • Severe menstrual pain

Treatment for histamine intolerance

There are many therapeutic options for individuals with histamine intolerance; however, not all patients respond the same to one treatment.

Here’s what you can do:

  • Dietary changes
  • Antihistamine drugs
  • Supplementation in DAO enzyme
  • Taking corticosteroids


When histamine intolerance is suspected in patients, immunological testing becomes a must to determine whether they have a concurrent food allergy that’s exacerbating their condition. In the end, histamine intolerance is a challenging condition to deal with, and identifying the triggers is crucial to improve your symptoms.


Author profile: Markus

Markus is a certified professional health coach with over a decade of experience in the field. He specialises in helping individuals navigate their health journeys, whether they are dealing with chronic conditions, working towards weight management goals, or seeking to improve their overall wellbeing.


Markus is also a prolific contributor to our blog, where he shares expert insights, tips, and advice to help you stay healthy. He is passionate about ensuring our readers have access to the latest research and information. For personalised health advice, consider scheduling a consultation with Markus.

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