Living with unexplained bloating, persistent headaches, or mysterious skin reactions can be frustrating—especially when standard allergy tests come back negative. For many Australians, the missing piece of the puzzle may be histamine intolerance. In this article we will explore how to treat histamine intolerance effectively so you can finally get relief from those nagging symptoms that seem impossible to pin down.
Histamine intolerance develops when the body cannot properly break down histamine, often due to reduced activity of the enzyme diamine oxidase (DAO). Common symptoms include digestive discomfort such as bloating and nausea, respiratory issues like nasal congestion, headaches or migraines, skin reactions, anxiety, insomnia, and even mood changes (did you know histamine acts as a hormone and neurotransmitter?). For women, symptoms often worsen around ovulation and premenstrually—a pattern I see repeatedly in clinic. Unlike true allergies, this condition creates a build-up of histamine in your gut that can affect multiple body systems. Treatment matters because chronic histamine overload can significantly impact your daily activities, sleep quality, hormonal balance, and overall health.
Identify histamine intolerance/DAO deficiency
First things first, do you have a histamine intolerance? Many people come to us convinced that histamine is the source of their symptoms. Realistically there could be other, or likely multiple causes. Symptoms of histamine intolerance typically appear within up to a few hours after consuming histamine rich foods, not days like IgG food intolerances. That’s why we recommend taking the Histamine Intolerance Test (DAO) along with our IgG blood tests to identify all possible trigger foods. This is a simple blood test to reveal whether you have low levels of diamine oxidase (DAO), the enzyme responsible for breaking down histamine in the gut. The test results will help you understand whether your symptoms are being driven or worsened by an underlying histamine intolerance. It’s similar to a lactose intolerance, in the sense that we need the enzyme lactase to break down lactose (the sugar in cows milk) in the gut.
ImuPro’s DAO test is the only DAO test available directly to consumers in Australia. It’s a blood serum test conducted in specialised certified German laboratories. Both the histamine and IgG tests can be conducted on a single serum sample.
What to do next
Once you have your results, you will understand your DAO production on a colour graded scale. About 3 out of 100 people have significantly low DAO levels, with roughly 20% having moderately reduced enzyme activity. If you fall into this category, below are some important next steps to take.
- Reduce dietary DAO blockers
This is different to a low histamine diet. DAO blockers are any substance that blocks the activity of our DAO enzyme. Classic examples are alcohol. All alcohol inhibits our DAO enzyme activity. Some people notice a worsening of symptoms after red wine, which is both DAO blocking and a rich source of histamine itself. Some medications like ibuprofen, naproxen, proton pump inhibitors and antibiotics can block DAO activity.
- Minimise dietary histamine load
Managing what you eat is a cornerstone of feeling better when you have a true histamine intolerance. But it can easily become far too restrictive when you Google “high histamine foods” and come back with hundreds of contradicting lists.
This is why it’s important to understand that food doesn’t contain a static amount of histamine. The histamine content depends on several factors including age/storage time, pH, method of processing, temperature, presence of histamine producing bacteria, freshness or rawness. So, you could have the same fish, stored in different ways and only one causes you to have a reaction. Or, for example, drinking some lime juice will not induce the same histamine response as a glass of wine and aged cheese.
So, there’s a sort of hierarchy of histamine foods (from high to low):
-
- Alcoholic beverages, especially champagne, red wine, wheat beer
- Cheese, especially hard cheese and aged cheese such as Parmesan, Edam, Emmental, Gouda, Camembert / Brie, Tilsit
- Cocoa and products containing cocoa, such as chocolate
- Salami and other cured meats
- Nuts, especially cashews and walnuts
- Tomatoes, ketchup
- Citrus fruit, strawberries, pears, pineapple, banana, kiwi
- Legumes
- Sauerkraut
- Spinach
- Vinegar
- Seafood and fish, if it was stored for a prolonged period and/or if the refrigeration chain was interrupted, smoked /cured. Fresh fish contains hardly any histamine.
It’s about the timing and the dosage. You may be able to successfully break down a couple of the lower-level foods in one meal. However, if you combine several of these, you may experience symptoms. In the same way, someone with a lactose intolerance can usually tolerate small amounts of cows milk, but anything over 12g will send them to the bathroom.
Start by eliminating high-histamine foods for 5 weeks, then gradually reintroduce them one at a time to identify your personal tolerance levels. Focus on fresh foods prepared at home—the fresher the food, the lower the histamine content. Opt for fresh meat and fish rather than processed or aged varieties, choose fresh vegetables over canned or pickled options, and select fresh dairy products if tolerated.
- Check your DAO nutrient cofactors
Pay attention to your intake of nutrients that help DAO work properly—vitamin B6, copper, and vitamin C—is just as important as avoiding high-histamine foods themselves. Many people find it helpful to keep DAO enzyme supplements in their bag for social events or unavoidable situations. You can ask your GP to check your red cell copper level, or consider our hair mineral and metal analysis for a deeper look at your tissue mineral levels. Vitamin C through foods or wholefood powders is an excellent way to support the DAO enzyme and to stabilise our mast cells which can trigger histamine release more systemically.
- Support gut health
Gut health also plays a pivotal role in histamine management. Gut dysbiosis, particularly overgrowth of certain bacteria that produce histamine, can significantly increase circulating histamine levels. Supporting healthy digestion through targeted probiotics (choosing low-histamine strains like Bifidobacterium species), healing intestinal permeability, and addressing underlying digestive conditions like SIBO (small intestine bacterial overgrowth) can make a profound difference.
When to See a Professional
Consider seeking professional support if your symptoms don’t improve after several weeks of dietary changes, if you’re struggling to identify trigger foods, if you suspect multiple food sensitivities beyond histamine, or if you’re experiencing cyclical symptoms that suggest a hormonal component. A functional medicine approach examines root causes, using personalised testing—including food sensitivity testing, comprehensive stool analysis, hormone panels, and mineral analysis—alongside targeted supplements and dietary interventions.
About the author: Hannah Ashby BHSc (Naturopathy), BPsychSc
Hannah is passionate about health, food and caring for the human microbiome. In 6 years of clinical work as a naturopath she has analysed thousands of microbiome and functional digestive tests. She has featured in recent publications on Body & Soul and the 2025 UNSW microbiology symposium. She loves to provide treatments that are evidence based, using the power of the microbiome so you can feel your best.