Histamine Intolerance Symptoms, Causes & Effects

Over the next few weeks, we’ll be taking an in-depth look at histamine. What it is, how it affects you, and what you can do to manage it naturally.

Let’s begin by looking at the difference between an intolerance and an allergic reaction. An allergic reaction is when the body naturally responds to an external ‘factor’ which irritates your body. Things such as pollen, dust or animal dander. This in turn, can cause a runny nose, or sneezing. These reactions can be mild or severe. You may think that you’re having anaphylactic attack if symptoms are severe.

Histamine intolerance is when your body is making too much of a substance called histamine. It overloads your immune system. Many times there are no obvious causes. You might not have an allergy to grass, foods or chemicals. However, something triggered your immune response, putting it into overdrive. This causes symptoms such as itching, hives, watery eyes, runny nose and so on.

Hopefully, I’ll be able to give you an understanding of what is going on in your body. What to look out for when the doctor’s say "there’s nothing wrong” when you still don't feel "quite right", and a few more tips on healthy eating.

What is Histamine?

Histamine is a naturally occurring chemical in your body. It’s made when the amino acid histidine is broken down in your gut. When your immune system discovers an allergen it knows it doesn’t belong. It reacts with an inflammatory response. You experience this inflammation as itching, redness, heat, pain and so on.

Believe it or not, it's vital for your digestion. It helps to release enzymes, and increase acidity in your stomach. It is then broken down in the intestines by another enzyme – Diamine Oxidase (DAO).

What are the symptoms?

There are many common symptoms of histamine intolerance. Perhaps you have experienced some of these yourself?

  • Hayfever – congested nose, runny nose, watery nose, headache, general malaise, sneezing, coughing
  • Eczema & atopic dermatitis – itchy skin, redness, heat, pain
  • Allergic reactions - sneezing, wheezing, itchy eyes, red rash
  • Painful period – heavy menstrual cycle, cramps, headaches
  • Urticaria – itchy skin, hot red welts, pain, blistering, swelling
  • Gastrointestinal upset/Irritable bowel syndrome (IBS) – nausea, diarrhoea, flatulence, stomach ache, bloating
  • Migraine/headache
  • Asthma or, difficulty breathing
  • Anxiety
  • Swelling of lips, eyes

What are the causes?

Symptoms of an intolerance can occur in many parts of your body. Often, you might not even think they are related to an intolerance. One person’s reaction may even be quite different to the next.


Hayfever is generally caused by pollen in the air. It can also be caused by dust, dust mites, airborne moulds, and grasses/weeds. Your immune system sees them as invaders and seeks out to destroy them.

Painful cycles

Painful period symptoms may be caused by high histamine levels which increase your oestrogen levels. This then increases blood flow to the uterus. Cramping also occurs from raised prostaglandins due to the inflammation. This results in heavy periods and painful cramping. Increased oestrogen levels can then cause further histamine production. It’s a vicious circle.

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) occurs due to irritation in the intestines that causes gastrointestinal symptoms. This prevents your digestion and absorption from working properly. This could be due to not having enough of an enzyme called diamine oxidase (DAO). Histamine breakdown in the intestines needs DAO. Without enough DAO to break it down, your histamine levels naturally rise.

Poor Digestion

Poor digestion can also be due to having antihistamines such as Zyrtec. These medications affect the receptors of gastric acid secretion. Reducing acidity in your stomach lowers the number of enzymes being released. Again, affecting food being broken down and, absorption of nutrients further down in the intestines.

High Histamine Foods

Certain foods are naturally high in histamine. As a result, this can aggravate any underlying health issues. Regularly eating foods with high levels can lead to an intolerance. To follow a low histamine elimination diet we have to understand the histamine rich foods. The foods to monitor include:

  • Strawberries
  • Raspberries
  • Chickpeas
  • Kiwi
  • Tomato/tomato paste
  • Avocado
  • Soy beans
  • Banana
  • Orange/lemon/lime
  • Smoked meats
  • Peanuts
  • Kombucha (fermented foods)
  • Sauerkraut
  • Pineapple
  • Papaya
  • Eggplant
  • Canned foods like tuna

What can you do to prevent histamine taking over your life?

This week, we've covered all of the background knowledge you need to understand histamine and the reactions it commonly causes. In our next article, we'll be talking about what you can do to control the levels within your body and reduce the symptoms of histamine intolerance.

One of the main contributors to histamine intolerance is SIBO and both can be explored in my Gut Fix Program where I take you through my steps to healing your gut.

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