What do itchy skin, bloating, vertigo, shortness of breath, and anxiety have in common?

Answer – they are all potential symptoms of excess histamine, or histamine intolerance.

If you ask Google to list out symptoms of excess histamine you get a huge list which looks like this:

Common Symptoms by Body System

• Head and Nervous System:

  • Headaches or migraines

  • Brain fog or trouble focusing

  • Dizziness, vertigo, or light headedness

  • Anxiety, nervousness, or sleep disturbances and insomnia

• Skin:

  • Flushing or sudden redness

  • Hives (urticaria), red welts, or itchy skin

  • Eczema flare-ups

• Digestive Tract:

  • Bloating, gas, or post-meal fullness

  • Diarrhoea or abdominal cramps

  • Nausea, vomiting, or acid reflux

• Nose and Airways:

  • Nasal congestion or a constant runny nose (rhinitis)

  • Frequent sneezing

  • Shortness of breath, wheezing, or asthma-like symptoms

• Cardiovascular System:

  • Heart palpitations or a fast heart rate (tachycardia)

  • Low blood pressure (hypotension) or near-fainting

• Hormonal:

  • Heavier or more painful menstrual periods (dysmenorrhea)

(copyright Google search).

There are some interesting features of histamine that make it worth taking a bit of time to consider.

It’s in a lot of different foods and drinks

Anytime you have a food where there has been:

• some kind of ageing process - think cheeses, charcuterie, wine…all my favourites!

• some kind of treatment with a culture / bacteria – think kefir, yogurt, sauerkraut, kimchi, kombucha, beer, wine…anything fermented

• a period of the food sitting around – like your leftovers in a fridge

• something containing protein which is cooked, simmered or smoked at low heat for a long time, like bone broth, or long slow cooking of meat, or smoking of fish

…then there is likely to be a high level of histamine in that food or drink. This is because the amino acid histidine is converted by the bacteria/ ferments / cultures, or also by enzymes, into histamine.

Your body – and the bacteria you host - also make histamine

Your body also makes histamine by converting the same amino acid (from proteins, remember) into histamine. This happens mainly in specialised cells called mast cells, but also by specialised immune cells called basophils. Mast cells are found throughout the body, but especially in areas where the body “interacts” with the outside environment, like the mucous membranes, the lining of the gut, the mucosal lining of the lungs, the skin. They are also found around lymph nodes and in the brain and its protective covering.

But don’t forget that we play host to vast communities of bacteria, in the gut, but also in lots of other places – lungs, mouth, vagina, skin, etc. Some of these bacteria can also make histamine (including some you can buy in a bottle, like some strains of lactobacillus).

But if histamine in excess causes all these symptoms, why does our body make it?

Because it’s really useful in fighting off stuff! The body is wise, it does not do things unnecessarily. Histamine:

• acts as an immune signaller, so that the white blood cells  / immune “super hero” cells are alerted into action,

• increases short term blood vessel permeability or “leakiness” so that those fighter immune cells can get into tissues, superhero cloak flying behind them, and get down to business,

• increases mucous production so that invaders e.g. in the lungs / airways are flushed out. This can also happen in the gut – a histamine reaction might also be involved in short term diarrhoeas, also to flush the baddies out,

• is toxic to lots of “invaders”, like parasites, and will go into battle against them.

That’s why we make the histamine – it’s helpful to us.

But it also has a nervous system / brain function – histamine is also a neurotransmitter and is involved in all sorts of stuff like wakefulness and keeping other brain chemicals in check. That’s why when there is too much histamine hanging around, the symptoms can be felt in many different bodily systems – it’s not just the itchy skin, excess mucous and sneezing – histamine can also be involved in mood (anxiety, restlessness), sleep disruption, brain fog, etc.

So 2 clients came with different sets of symptoms:

• Client one was a teenager, and suffered anxiety to the point that it was severely affecting her life, as well as various food intolerances, and other symptoms including stomach cramps, nausea, and the curious symptom of scratching an itch only to have another itch appear somewhere else on the body.

• Client two had childhood wheeziness and breathlessness, chronic itching of the scalp and other areas of the body, bloating after meals, over sensitivity to noise / environment, and restless legs.  

I ran a test called DNA histamine for each of these clients. Now before we jump into thinking that the histamine in both these cases is “the root cause”, there were also other things going on that we worked with. There is rarely one root cause, we at the New School of Nutritional Medicine work with the whole person, always.

But back to histamine. When the body clears histamine, it does so through 2 enzymes:

 DAO (diamine oxidase) clears histamine mainly from outside the cell including in the gut. It is mainly clearing exogenous (outside the body) sources – from food and gut bacteria production of histamine

HNMT (histamine n-methyl transferase) clears histamine mainly from inside the cell including in the brain and lung cells / bronchial cells. It mainly clears histamine from endogenous sources – the mast cells production of histamine.

Both these clients were found to have genetic SNPs, or “glitches” which meant that they don’t clear histamine so well (their anonymised results are at the bottom if you’re interested).

So we worked on what these clients can do to help themselves. This might include some temporary dietary changes to see if ingested histamine makes things worse, but also supporting them with other strategies. See the green writing in the enzyme diagram above? Those are co-factors – or friends that support the enzyme when it is doing its work. So HNMT is a methylation enzyme – it detoxes histamine by methylating it (a whole other subject! See the “Clean up your genes” blog from March 2025 for a bit more on methylation). Both clients were supported in how well they methylated; but also you can see that the DAO enzyme needs nutrients – namely iron, B12, B6, copper and vitamin C to do its job, so often histamine clients need to eat diets rich in these nutrients in order to help themselves.

If you are interested in this subject and particularly in the nervous system / brain aspects of histamine, then you might want to look into the work of the orthomolecular scientists (see my blog from May 2023) such as Dr Carl Pfeiffer and Dr William Walsh.

If you run through that list from Google at the top of this blog and find yourself ticking lots of boxes, then you might want to find out for yourself if you are clearing histamine as well as you might be. I would be more than happy to help! You can book a discovery call here.

Here’s to health – and good histamine clearance!

Marie

DNA Histamine results

Client 1:

Client 2: