Still Blaming Hay Fever? It Might Be Histamine Intolerance
- 1 day ago
- 3 min read
If your "hay fever" seems to show up year-round, gets worse after a glass of wine or a plate of cheese, or never quite responds to antihistamines as it should, the cause might not be pollen at all. It could be histamine intolerance, a condition that's often mistaken for allergies because the symptoms look so similar.
What is Histamine Intolerance?
Histamine is a natural chemical involved in your immune response, digestion, and nervous system. Normally, an enzyme called diamine oxidase (DAO) breaks down histamine from food before it builds up in the body. When DAO activity is low, or when histamine intake outpaces the body's ability to clear it, histamine accumulates and can trigger a wide range of symptoms, including ones that mimic allergies.
Unlike a true food allergy, histamine intolerance isn't an immune reaction to one specific food. It's more of a tipping point: a build-up from multiple sources at once, until your body's histamine "bucket" overflows.
Common Symptoms
Because histamine affects so many systems in the body, symptoms can be wide-ranging and easy to misattribute to something else:
Sneezing, congestion, or itchy eyes that don't improve with typical hay fever treatment
Headaches or migraines
Flushing or hives
Digestive symptoms such as bloating, cramping, or diarrhoea
Fatigue or brain fog
A racing heart or dizziness after certain meals or drinks
What Causes DAO to Be Low?
DAO deficiency can come from a mix of genetic, gut, and lifestyle factors. Research points to several contributors:
Genetics - certain gene variants are linked to naturally lower DAO activity
Gut health - intestinal inflammation, dysbiosis (Understanding Your Gut Blog), or conditions like IBS can impair DAO production, since it's made largely in the small intestine
Medications - some common drugs are known to inhibit DAO activity
Hormones - DAO activity can shift with the menstrual cycle and pregnancy, which is part of why some women notice symptoms easing during pregnancy and returning afterwards
Diet - histamine-rich or histamine-releasing foods and drinks (aged cheese, cured meats, fermented foods, alcohol, especially wine and beer) add to the overall load.
Why This Matters for "Hay Fever"
Because histamine is also the chemical your body releases during a genuine allergic reaction, histamine intolerance and seasonal allergies can look almost identical. The key difference is that with histamine intolerance, symptoms often continue outside of pollen season, worsen after specific foods or drinks rather than outdoor exposure, and don't fully resolve with standard antihistamines.
A Functional Medicine Approach
Rather than reaching straight for symptom control, a functional approach looks at why histamine is building up in the first place. This can involve:
Reviewing gut health, since dysbiosis and inflammation are closely linked to lower DAO activity
A temporary lower-histamine diet to reduce the overall load while identifying triggers
Looking at hormonal patterns, particularly for women who notice symptoms shifting across their cycle
Supporting the gut lining and microbiome long term, rather than avoiding trigger foods indefinitely
In Summary
Histamine intolerance happens when histamine builds up faster than the body can clear it, often due to low DAO enzyme activity
Symptoms overlap heavily with hay fever and allergies, which is why it's so often missed
Gut health, genetics, hormones, medications, and diet can all affect DAO activity
A functional approach looks at the root cause rather than just managing symptoms
A Final Word
If your seasonal symptoms never quite make sense, or persist well outside of pollen season, it may be worth looking beyond hay fever. Understanding what's really driving your histamine levels is the first step toward lasting relief, not just symptom control.
Book a free discovery call to find out how Functional Medicine can support you, if histamine intolerance could be behind your symptoms, or follow @tracytredouxhealth for regular nutrition, healthy ageing and Functional Medicine insights.
Comments