How to recognize a histamine intolerance

A histamine intolerance means your body can’t clear histamine fast enough, so it builds up in your blood and triggers symptoms like headaches, flushing, a stuffy nose, or stomach trouble, usually within minutes to a few hours after eating histamine-rich foods such as aged cheese, red wine, or spinach. It comes from reduced activity of the enzyme diamine oxidase (DAO), which normally breaks histamine down in your gut. An estimated 1 to 3% of people deal with it (1), and because the symptoms overlap with so many other things, spotting the pattern is usually the first real step.

In short:

• A histamine intolerance is caused by reduced activity of the DAO enzyme, not simply by eating “too much” histamine.
• Symptoms of histamine intolerance can appear within minutes to a few hours after eating histamine-rich foods.
• Common triggers include aged cheese, red wine, spinach, tomatoes, and fermented foods.
• A DAO blood test alone is not considered a reliable way to confirm histamine intolerance.
• A DAO enzyme supplement, such as DAO Plus, may support histamine digestion.

What Is a Histamine Intolerance?

A histamine intolerance is a reduced ability to break down histamine, a compound your body produces naturally and that’s also present in many foods. It develops when the enzyme DAO can’t clear histamine quickly enough in your gut, allowing it to build up in your bloodstream and trigger symptoms.

Most food intolerances, such as a lactose intolerance, come from a shortage of the enzyme needed to digest a specific substance. Histamine intolerance works differently: your body does produce DAO, just not enough relative to how much histamine you’re taking in and generating. DAO is mainly responsible for breaking down histamine in the gut wall before it reaches your bloodstream, while a separate enzyme, HNMT, handles most histamine breakdown elsewhere in the body (2). When gut-level DAO activity falls short, dietary histamine gets absorbed instead of broken down. Histamine intolerance was only described as its own condition at the start of this century, and researchers estimate it affects around 1 to 3% of people (1).

What Are the Symptoms of a Histamine Intolerance?

The symptoms of histamine intolerance vary widely from person to person and often overlap with other conditions, which is part of why it’s easy to miss. They can include:

• Headaches and migraines
• Brain fog or dizziness
• Restlessness or sleeplessness
• Heart palpitations
• A runny or stuffy nose
• Eczema, itchiness, or flushed, warm skin
• Digestive complaints, such as bloating or stomach pain

These symptoms of histamine intolerance typically show up within minutes to a couple of hours after eating high-histamine foods, including aged cheese, cured meats, spinach, tomatoes, mushrooms, eggplant, and red wine.

What Causes a Histamine Intolerance?

Several underlying conditions can reduce how well your body clears histamine, including gastrointestinal disorders, certain infections, and cardiovascular disease. When one of these is already part of the picture, it becomes more likely that excess histamine is contributing to your symptoms, on top of, or instead of, whatever else is going on.

How Is a Histamine Intolerance Diagnosed?

There’s no single test that reliably confirms a histamine intolerance. A blood test measuring DAO activity is widely used, but research shows it doesn’t line up well with actual symptoms: in a study of over 1,000 adults, DAO levels didn’t predict who reported histamine-related complaints, except at very low levels (3). Other research found the test can distinguish histamine intolerance fairly well from healthy people, but performs much more weakly when compared against people with ambiguous, low-probability symptoms (4).

Because a blood test alone isn’t conclusive, an elimination diet under the guidance of a dietitian is usually the most practical way to find out whether histamine is really behind your symptoms.

How Can You Manage a Histamine Intolerance?

A first, obvious step is reducing how much histamine you take in through food. A low-histamine diet can help manage symptoms of histamine intolerance and reduce discomfort, but it’s an intensive diet that should always be followed under the guidance of a doctor or dietitian, since cutting out too many foods for too long can create its own problems.

A DAO enzyme supplement is another option some people use alongside dietary changes. In practice, a DAO supplement is best seen as one tool to discuss with your dietitian, not a guaranteed fix on its own (5,6).

What Does a DAO Enzyme Supplement Do?

DAO Plus and DAO Mini are Intoleran’s DAO enzyme supplements. DAO helps with the digestion of histamine.

You can also support your body’s own DAO production with nutrients such as vitamin C, vitamin B6, quercetin, zinc, and copper, all found in Cozidase. Cozidase provides the building blocks for your body’s own DAO enzyme production and has a positive effect on the immune system*.

* Vitamin C

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Living With a Histamine Intolerance

A histamine intolerance can feel like a confusing, moving target, but it doesn’t have to stay that way. With the right combination of diet and, where it fits, supplementation, it’s realistic to get your symptoms under control and enjoy food again.

Not sure where to start? Reach out to our team we’re happy to help you think through your options.

If your symptoms persist, you’re losing weight without trying, or you keep cutting out more and more foods, talk to your doctor or a dietitian.

Sources

1. Comas-Basté O, Sánchez-Pérez S, Veciana-Nogués MT, Latorre-Moratalla M, Vidal-Carou MC. Histamine Intolerance: The Current State of the Art. Biomolecules 2020;10(8):1181.
2. Patel RH, Rahimi N. Biochemistry, Histamine. StatPearls, 2026.
3. van Odijk J, et al. DAO activity and self-reported symptoms in a Swedish adult cohort. Nutrients 2023;15(13):2887.
4. Arih K, et al. Diagnostic accuracy of serum DAO for histamine intolerance. Nutrients 2023;15(19):4246.
5. Komericki P, et al. Histamine intolerance: results of a randomized, double-blind, placebo-controlled trial. Wien Klin Wochenschr 2011;123:15–20.
6. Reese I, et al. Vorgehen bei Verdacht auf Unverträglichkeit gegenüber oral aufgenommenem Histamin. AWMF S1 Guideline 061-030, 2021.