Headaches after red wine, flushing after aged cheese, a stuffy nose or an upset stomach after leftovers: many people come to suspect histamine. "Histamine intolerance" is now a popular self-diagnosis, with its own diets, blood tests and a supplement, the enzyme DAO (diamine oxidase), sold to help break down histamine in food.
The research is less settled than the marketing. A major 2021 allergy guideline from Germany, Switzerland and Austria says there is no reliable way to diagnose it and does not recommend DAO supplements. That does not mean the symptoms are imaginary. It means that working out what is really causing them takes care. This guide covers what the evidence shows.
The short version
- Histamine intolerance is a proposed condition, not a proven one. The idea is that some people cannot break down histamine from food fast enough. A 2021 German, Swiss and Austrian allergy guideline says there is "no reliable procedure" to diagnose it.
- Blood DAO tests do not diagnose it. The same guideline says measuring DAO in blood "has no diagnostic value."
- Blinded tests rarely confirm it. In a 59-person study, histamine intolerance was ruled out in about 85 percent of people who suspected it, and about 63 percent reacted to a placebo.
- DAO supplements have not been shown to work. Around six small trials have tested them, and none clearly beat placebo on its main goal. The guideline does not recommend them. Most DAO comes from pig kidney, so avoid it if you have alpha-gal syndrome (a red-meat allergy usually triggered by tick bites) or a pork allergy.
- A short, structured low-histamine diet with reintroduction is the approach the guideline suggests, ideally with a dietitian. Avoid long-term blanket restriction.
- Rule out other causes first. Flushing, hives or gut symptoms can come from allergy, mast cell disorders (where the immune cells that store histamine release too much), celiac disease, IBS or food poisoning. Swelling of the throat or trouble breathing is an emergency.
What histamine intolerance is
Histamine is a natural chemical the body uses in allergic reactions, digestion and the brain. It is also present in foods, especially aged, fermented, cured or poorly stored ones. The body breaks down histamine in two ways: an enzyme called diamine oxidase (DAO), made mainly in the gut, handles histamine from food, and another enzyme, histamine N-methyltransferase (HNMT), breaks down histamine inside the body's own cells.
Histamine intolerance is the idea that some people take in more histamine than their DAO can handle, causing symptoms such as headaches, flushing, a runny nose or gut upset. The name was borrowed from lactose intolerance. The difference is that lactose intolerance has a proven enzyme shortfall and a validated test (see our lactose intolerance guide); histamine intolerance has neither yet. The 2021 guideline therefore uses the more cautious phrase "adverse reactions to ingested histamine."
Nobody knows how common it is. The often-quoted figure of "about 1 percent" traces back to a 2004 German textbook, not to a population study.
Is histamine intolerance real?
Some people clearly react to histamine-rich meals, and everyone reacts to very large amounts: spoiled fish containing lots of histamine causes "scombroid" food poisoning in anyone who eats it. The question is whether a distinct group of people reacts to the ordinary amounts in everyday food. Blinded challenge studies, where neither patient nor researcher knows whether a drink contains histamine or a placebo, have mostly failed to show this reliably:
- Healthy people react too. In a 2004 trial, 75 mg of histamine, an amount found in normal meals, caused symptoms in 5 of 10 healthy women with no history of food problems.
- Reactions did not repeat. In a 2011 Austrian study, 39 patients who reacted to histamine in an open test entered a blinded test, and their symptoms could not be reproduced; people "reacted sometimes unexpectedly and randomly."
- Most suspected cases were ruled out. In a 2023 German study of 59 people referred with suspected histamine intolerance, it was ruled out in 84.7 percent, and 62.7 percent had symptoms after the placebo. Objective symptoms after histamine but not placebo occurred in only 4 people, and another 5 were judged possible cases.
- History is a poor guide. Of 157 people with chronic hives, only 2 were positive on all three of history, diet response and a blinded histamine challenge.
Some researchers, mainly in groups that study DAO, see the condition as well established and consider improvement on a low-histamine diet enough to confirm it. The formal multi-society guideline disagrees, and concludes that the diagnosis can only be made, or ruled out, based on symptoms and careful testing of foods.
Histamine intolerance symptoms, and what else they could be
Symptoms blamed on histamine include flushing, itching, hives, headache, a runny or stuffy nose, bloating, diarrhea, nausea, abdominal pain and a racing heart, usually within minutes to about four hours of eating. Women often report worse symptoms before their period. The trouble is that every one of these symptoms has other, more common causes.
| Symptom | Other causes to rule out |
|---|---|
| Flushing | Mastocytosis (too many mast cells), hormone-producing tumors |
| Itching, hives | Chronic urticaria (long-lasting hives), allergy, skin conditions |
| Diarrhea, abdominal pain | IBS, lactose intolerance, fructose malabsorption, celiac disease, inflammatory bowel disease |
| Runny or stuffy nose | Allergic or non-allergic rhinitis |
| Dizziness, low blood pressure, racing heart | Anaphylaxis, mastocytosis |
Adapted from the differential diagnosis table in the 2021 German, Swiss and Austrian guideline, with IBS and allergy added by NutraSmarts.
Histamine-rich foods overlap with other triggers. Red wine and aged cheese are also common migraine triggers, and histamine-rich meals often contain FODMAPs (such as onion, garlic or wheat) or lactose (milk, soft cheeses), so a reaction blamed on histamine may come from something else; see our low-FODMAP guide and gluten sensitivity guide. Histamine intolerance is also different from a food allergy, which involves allergy antibodies called IgE and can be life-threatening, and from mast cell activation syndrome, where the body releases its own histamine; DAO only acts on histamine in food. MSG is another common suspect after restaurant meals; see our MSG sensitivity guide for what blinded studies found.
- Emergency: swelling of the lips, tongue or throat, wheezing, trouble breathing, fainting or collapse. Use epinephrine if prescribed and call emergency services.
- See a doctor for unexplained weight loss, blood in the stool, persistent diarrhea or vomiting, flushing with fainting or a racing heart, or symptoms that keep getting worse.
Histamine intolerance tests: which help and which do not
- Blood DAO tests: the guideline states that DAO measured in blood "has no diagnostic value," because blood levels do not reflect DAO activity in the gut. In a 2023 study of 249 people, the commercial cutoff identified many people correctly against healthy volunteers, but separated poorly between patients, and the authors concluded the diagnosis "should not solely rely on DAO measurements."
- DAO gene (AOC1) tests: sold online, but no guideline endorses them for diagnosis.
- Histamine skin prick test read at 50 minutes: one clinic study used it, but it has not been confirmed by other groups, and it does not show how fast you break down histamine from food.
- Blood or urine histamine, stool histamine, and IgG food panels: not recommended. A 2008 position paper from the European allergy academy advises against IgG4 food testing for food-related complaints, since food IgG4 antibodies are a normal response to eating a food. See our guide to at-home gut and food sensitivity tests.
- A blinded oral histamine challenge is the most rigorous test, but it is a supervised hospital procedure with no standard protocol. Never try histamine doses at home.
What to do instead, step by step (the guideline's approach):
- See a doctor, usually your family doctor first and then an allergist or gastroenterologist if needed, to rule out allergy, celiac disease, IBS, inflammatory bowel disease and mast cell disorders.
- Keep a food and symptom diary: what you ate, how fresh it was, any alcohol, and when symptoms started.
- Try the short, structured low-histamine diet below, ideally with a registered dietitian, then reintroduce foods one at a time.
Low-histamine diet: food list and phases
Histamine levels vary hugely, even within the same food, depending on ripeness, storage time and processing. Foods most often high in histamine include:
- Aged and ripened cheeses, especially raw-milk cheeses (fresh cheeses usually contain very little).
- Cured and fermented meats such as salami and dry sausages.
- Canned, smoked or poorly stored fish, such as tuna, mackerel and sardines. Fresh, well-chilled fish is usually low.
- Fermented foods such as sauerkraut, soy sauce and some vinegars.
- Alcohol, especially red wine, which on average contains more histamine than white wine or beer. Alcohol may also slow histamine breakdown. Wine also contains sulfites, a separate issue covered in our sulfite sensitivity guide.
Usually low in histamine: fresh meat and poultry, fresh fish that was chilled quickly, fresh (unripened) cheeses such as mozzarella and cottage cheese, most fruit, and legumes. Freshness matters more than the food type.
Many low-histamine lists also ban "histamine liberators" such as strawberries, citrus, tomatoes, chocolate and egg white. The guideline says there is no reliable evidence that such foods exist or matter clinically, and a review of 10 published low-histamine diets found they disagreed widely; only fermented foods were excluded by all of them.
The guideline describes a three-phase approach, similar in spirit to the low-FODMAP diet:
| Phase | What you do | How long |
|---|---|---|
| 1. Reduce | A mostly plant-based mixed diet lower in histamine and other biogenic amines (similar compounds that build up as food ages or ferments), with fresh foods | 10 to 14 days |
| 2. Test | Reintroduce suspected foods one at a time to find your personal tolerance | Up to 6 weeks |
| 3. Long term | Eat as widely as you can, limiting only foods that reliably cause problems | Ongoing |
Does the diet work? As of the 2021 guideline, the studies were observational and randomized trials were lacking. Since then, a small randomized crossover trial of 18 people reported fewer gut and skin symptoms on a low-histamine diet than on a mixed diet, though diets cannot be blinded. In uncontrolled studies of chronic hives, around half to 60 percent of people improved, but in the 157-person study, diet response did not match blinded histamine testing, so the benefit may not come from cutting histamine itself.
Practical tips: eat fresh food, chill fish quickly and eat it soon, freeze leftovers rather than keeping them for days, and reintroduce foods instead of cutting them forever. People on long, broad restriction diets can run low on nutrients such as protein, calcium, vitamin C, folate and fiber, and the guideline specifically warns against unnecessary restriction. A dietitian can help.
DAO supplements: what the trials show
DAO supplements contain the enzyme, usually from pig kidney (sold as DAOgest, DAOSiN and others), or from pea sprouts in "vegan" versions. Taken 15 to 30 minutes before a meal, they are meant to break down histamine in the food in the gut. They do nothing for histamine your own body releases.
We found around six human studies, five of them controlled, with fewer than 400 people in total, the longest lasting eight weeks:
- Histamine challenge (39 people, 2011): the authors reported significantly lower total symptom scores with DAO than with placebo (P = 0.014), the best controlled result for the enzyme. The 2021 guideline questions it, noting that the study's primary endpoint was not met and that the capsule maker supported the study.
- Chronic hives (22 people, 2018): hive scores did not differ from placebo overall; the improvement often quoted came from a small subgroup of people with low blood DAO.
- Migraine (100 people, 2019): attacks shortened on DAO (6.14 to 4.76 hours), but the placebo group also improved, and the difference between groups was not significant.
- Fibromyalgia (100 women, 2023): funded by a DAO maker; the main questionnaire scores did not differ significantly between groups.
- Insomnia (101 people, 2026): on the main sleep score, the placebo group improved more than the DAO group.
- Open-label pilot (28 people, 2019): symptoms improved without a control group, in a study run with the product's maker.
No adequately powered study has beaten placebo on the outcome it was designed to measure, and the protocol for a 400-person trial was published in 2024, with no results published that we could find as of November 2026. The guideline states that DAO supplementation "has not been scientifically proven to date and is not recommended." Lab work also raises a dose question: pig DAO lost activity quickly in simulated gut fluid, and one commercial capsule tested by an independent lab showed no measurable enzyme activity.
Pig-kidney DAO is an authorized novel food in the European Union, capped at 0.9 mg of DAO a day in three doses; in the US it is sold as a dietary supplement. Potency labels in HDU (histamine degrading units) are not standardized across brands. We found no published human trial of plant (pea sprout) DAO. If you still want to try DAO, treat it as a two to four week experiment alongside a diet diary, with a stopping date you set in advance, and see our DAO supplement ranking for how products compare.
Quercetin, vitamin C, B6 and probiotics
In PubMed searches in November 2026, we found no randomized trial in people with histamine intolerance for any of these:
- Quercetin reduces histamine release from immune (mast) cells in lab studies, a different mechanism from DAO. Its human allergy evidence is in hay fever, not histamine intolerance. See our quercetin guide.
- Vitamin C at 2 g a day lowered blood histamine by 38 percent in 10 healthy adults, but in test-tube studies it can also inhibit DAO, so "vitamin C boosts DAO" is not established.
- Vitamin B6, copper and zinc are often sold as DAO "cofactors." DAO is a copper-dependent enzyme, and some authors suggest correcting deficiencies of copper, vitamin B6 or vitamin C, but zinc is not an established DAO cofactor, and we found no human trial showing that supplementing any of these raises DAO or eases symptoms. Do not take high doses; copper, zinc and vitamin B6 all have safe upper limits.
- "Low-histamine" or "histamine-friendly" probiotics are chosen because the strains are not thought to make histamine; we found no published trial showing these products help, and a small probiotic trial in histamine intolerance (NCT07397962) is registered as completed but without published results. Some gut bacteria, including some lactobacilli, produce histamine.
- Stinging nettle and bromelain have only hay fever data or none.
Antihistamine medicines are a medical option for individual symptoms; the guideline notes they have not been tested in controlled trials for this condition. Talk to a doctor or pharmacist rather than self-dosing. For allergy symptoms more broadly, see our supplements for allergies guide and the allergy supplements hub.
Who should be careful
- Rule out other causes first. Allergy, mast cell disorders, celiac disease, IBS and other conditions can look the same. Throat swelling or trouble breathing is an emergency.
- Medicines. Some drugs inhibit DAO in lab tests, such as clavulanic acid (in amoxicillin-clavulanate), verapamil and metoclopramide; whether this matters at normal doses is not established. Never stop a prescribed medicine; ask your doctor or pharmacist.
- Pork allergy, alpha-gal syndrome or dietary rules. Most DAO comes from pig kidney, which is not vegetarian and not suitable for many halal or kosher diets. If you have alpha-gal syndrome (an allergy to red meat, usually triggered by tick bites) or a pork allergy, avoid pig-kidney DAO unless your allergist says otherwise; in one study, pork kidney was among the most allergenic foods for people with alpha-gal syndrome. Avoid pea-based DAO with a pea or legume allergy.
- Pregnancy and children. The placenta makes large amounts of DAO, so blood DAO rises sharply in pregnancy, and we found no DAO trials in pregnancy, breastfeeding or children. Do not start a restrictive diet for a child or during pregnancy without medical guidance.
- Avoid long-term blanket restriction. Reintroduce foods to find your real limits.
Frequently asked questions
What are the symptoms of histamine intolerance?
Symptoms blamed on it include flushing, itching, hives, headache, a runny or stuffy nose, bloating, diarrhea, nausea, abdominal pain and a racing heart, usually within minutes to about four hours of eating. Every one of these has other, more common causes, which is why it is hard to pin down. Swelling of the throat or trouble breathing is an emergency.
Is there a test for histamine intolerance?
Not a reliable one. A 2021 German, Swiss and Austrian allergy guideline says measuring DAO in blood has no diagnostic value and questions urine and stool histamine tests; a 2008 European allergy academy position advises against IgG4 food panels, and no guideline endorses DAO gene tests. A blinded oral histamine challenge is the most rigorous test but is a supervised hospital procedure. In practice, diagnosis rests on ruling out other causes and a structured diet with reintroduction.
What causes histamine intolerance?
The leading idea is an imbalance between the histamine you take in and your body's ability to break it down, mainly through the gut enzyme DAO. Alcohol may slow histamine breakdown, and some medicines inhibit DAO in lab tests, though whether that matters at normal doses is not established. None of these has been shown to cause a distinct condition, and the same symptoms often come from allergy, IBS, celiac disease or other problems, so ruling those out comes first.
Do DAO supplements work?
They have not been shown to. Around six small studies with fewer than 400 people have tested them, and none clearly beat placebo on its main goal; in a 2026 insomnia trial, the placebo group improved more. The 2021 guideline does not recommend DAO supplements. Some people try them as a short experiment before histamine-rich meals.
Which DAO supplement is best?
No DAO product has clearly beaten placebo in a trial, and label potency in HDU (histamine degrading units) is not standardized across brands, so our DAO supplement ranking compares products on things that can be checked: enzyme source, protection from stomach acid, label transparency and allergen fit. Most DAO comes from pig kidney, so avoid it if you have alpha-gal syndrome (a red-meat allergy usually triggered by tick bites) or a pork allergy unless your allergist says otherwise; it is also not vegetarian and not suitable for many halal or kosher diets. We found no published human trial of pea-sprout versions.
Which foods are high in histamine, and which are low?
Aged and raw-milk cheeses, cured and fermented meats such as salami, canned, smoked or poorly stored fish such as tuna and mackerel, fermented foods such as sauerkraut and soy sauce, and alcohol, especially red wine. Fresh foods, fresh fish that has been chilled quickly, and fresh cheeses are usually low. Levels vary widely with storage and ripeness.
Is histamine intolerance real?
It is a plausible but unproven condition. Some people clearly react to histamine-rich meals, but in blinded tests most suspected cases are not confirmed: in one study of 59 people, it was ruled out in about 85 percent and about 63 percent reacted to a placebo. The symptoms are real; histamine is often not the proven cause.
How long should you follow a low-histamine diet?
The 2021 guideline describes about 10 to 14 days of reduced histamine, then up to 6 weeks of reintroducing foods one at a time to find your tolerance, then a long-term diet that limits only foods that reliably cause problems. Long-term blanket restriction is not recommended.
How long does histamine intolerance last?
We found no studies that follow people with suspected histamine intolerance over years, so how long it lasts is unknown. The 2021 guideline's plan is short: about 10 to 14 days of reduced histamine, up to 6 weeks of reintroduction, then a varied diet that limits only foods that reliably cause problems. If symptoms continue or get worse, see a doctor, because another cause may be involved.
Can quercetin or vitamin C help histamine intolerance?
We found no published randomized trials of either in people with histamine intolerance. Quercetin reduces histamine release from immune cells in lab studies, and vitamin C lowered blood histamine in a small study of healthy adults, but in test tubes vitamin C can also inhibit DAO. Neither is a proven aid for this condition.
The bottom line
Histamine intolerance is a plausible idea with weak proof: no blood test diagnoses it and blinded tests rarely confirm it. That does not make anyone's symptoms imaginary. It means histamine is often not the trigger, and conditions from IBS to allergies can look the same.
If histamine-rich foods seem to bother you, rule out other causes first, then try a short low-histamine diet with structured reintroduction, ideally with a dietitian, and avoid long-term blanket restriction. DAO supplements have not been shown to beat placebo and are not recommended by the guideline, though some people try them as a short experiment. We found no published randomized trials of quercetin, vitamin C or "low-histamine" probiotics in this condition.