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There's no reliable test – not even the DAO blood test. Rule out other causes, eat low-histamine for 10–14 days, then test foods. The goal is variety, not bans.
Short answer: There is no reliable lab test – according to the guideline, even the DAO blood test tells you nothing useful. First have a doctor rule out other causes, then eat low-histamine for 10 to 14 days and spend up to six weeks bringing foods back one at a time in a test phase. The goal isn't a lifelong list of banned foods but varied meals that suit what you personally tolerate.
Histamine is a messenger substance your body makes itself, and it's also found in many foods – especially aged, fermented or not-quite-fresh ones. It is broken down mainly by diamine oxidase (DAO) in the gut and by histamine N-methyltransferase (HNMT) inside cells.
The usual explanation: if too little is broken down, histamine from food builds up and causes allergy-like symptoms (Maintz & Novak 2007). The guideline from the German-speaking allergy societies is cautious: the evidence for a causal link is limited and contradictory, and controlled studies are missing (Reese et al. 2021).
Nobody knows exactly how many people are affected; reviews estimate around 1 to 3% (Comas-Basté et al. 2020). According to the guideline, the intolerance is suspected far more often than it is confirmed.
An important distinction: histamine poisoning, for example from spoiled tuna or mackerel, is not an intolerance. Very large amounts of histamine cause symptoms in everyone.
Histamine acts through four receptors in many organs – which is why the symptoms are so varied. Typical ones are sudden facial flushing, itching, skin redness, nausea, diarrhoea and stomach pain, often headaches too; less often breathing or circulation problems such as dizziness or a racing heart.
The same symptoms often have other causes. The guideline lists what should be checked first:
| Symptom | Possible other causes |
|---|---|
| Flushing (red face) | neuroendocrine tumours, mastocytosis |
| Itching | urticaria (hives), other skin conditions |
| Nausea, vomiting | stomach or duodenal ulcer |
| Diarrhoea, stomach pain | inflammatory bowel disease, lactose intolerance, fructose malabsorption, coeliac disease, mastocytosis |
| Runny nose | allergic and non-allergic rhinitis |
| Shortness of breath, voice problems | allergic and non-allergic asthma |
| Drop in blood pressure, dizziness, racing heart | anaphylaxis, mastocytosis |
No reliable lab tests: According to the guideline, DAO activity in the blood tells you nothing useful – people with and without symptoms have similar values. Histamine in the blood and methylhistamine in urine are also viewed critically. Instead:
Related topics: FODMAP and IBS or gluten and coeliac disease.
| Phase | How long | Goal |
|---|---|---|
| 1. Elimination | 10 to 14 days | Reduce symptoms as much as possible: a varied, veg-heavy diet low in histamine and other biogenic amines, with regular, light meals |
| 2. Test phase | up to 6 weeks | bring suspect foods back one at a time, relax strict rules, find out what you personally tolerate |
| 3. Long-term diet | long term | eat a varied diet that covers your needs, avoiding only what you have shown you don't tolerate well |
The aim is to move you from blanket bans to a diet that fits you, ideally with support from a dietitian. Children and anyone pregnant or breastfeeding shouldn't restrict their diet heavily for long without professional support.
Histamine levels vary hugely depending on ripeness, storage time and processing – according to the guideline, from barely detectable to around 2,000 mg per kilogram in Emmental and smoked mackerel. Lists are therefore only a rough guide. A widely used one comes from the Swiss Interest Group Histamine Intolerance (SIGHI); it is based to a large extent on the experience of people with symptoms. In short:
| Food group | Often less well tolerated | Usually well tolerated |
|---|---|---|
| Fish | tinned, smoked or marinated fish, tuna, mackerel, anchovies | freshly caught or frozen fish, thawed quickly |
| Meat | dried, smoked or long-aged meat products | fresh poultry and beef, kept well chilled |
| Dairy | long-aged cheese | milk, butter, cream, cream cheese, mozzarella, quark, young cheese |
| Veg | sauerkraut, tomatoes, spinach, aubergine, avocado | most other veg, fresh or frozen |
| Grains | – | rice, potatoes, oats, millet, corn and other grains |
| Drinks and seasonings | alcoholic drinks, wine and balsamic vinegar, soy sauce, yeast extract | water, herbal tea, fresh herbs, mild spices |
According to the guideline, alcohol also slows down the breakdown of histamine.
Many lists name "histamine liberators" such as citrus fruit, strawberries, tomatoes, chocolate or certain nuts, which are said to release the body's own histamine. According to the guideline, neither their presence in food nor their role in symptoms has been reliably shown. So don't cut them out just in case – test them one at a time.
Some medicines (such as acetylcysteine, metamizole, verapamil, metronidazole, metoclopramide) are said to inhibit DAO; the evidence is mixed. Don't stop taking anything on your own – talk to your doctor about your suspicion.
Only take any supplement after talking to your doctor:
More background in our guide to the gut and microbiome.
Common mistakes: relying on a DAO blood test; eating from a long list of banned foods for good (risk of a one-sided diet); keeping leftovers in the fridge for several days.
More: Histamine intolerance: food list and low-histamine recipes.
Get recurring symptoms after eating checked by a doctor before you cut back your diet heavily for good – your GP, an allergy clinic or a gastroenterologist are the places to go. If you have shortness of breath, swelling in your face or throat, severe dizziness or circulation problems after eating, call the emergency number straight away (112, or 999 in the UK): it could be an allergic reaction that needs treating quickly.
No, not even a DAO test tells you anything useful. The diagnosis is clinical: rule out other causes, go through the elimination and test phases and, if needed, a challenge test under medical supervision.
Strictly for only 10 to 14 days, followed by a test phase of up to six weeks. After that, eat as varied a diet as possible, leaving out only what you have shown you don't tolerate well.
Not across the board. Their role as histamine liberators hasn't been reliably shown, although tomatoes do contain some histamine themselves. Use the test phase to find out what amounts you tolerate.
Neither is convincingly backed by evidence. Vitamin B6 has an EFSA upper limit of 12 mg a day – only take supplements after talking to your doctor.
No. An allergy is the body reacting to a specific protein; with histamine intolerance, a problem with breaking down histamine is suspected. Because the symptoms are similar, an allergy check is an important first step.
This article doesn't replace advice from a doctor or dietitian. If you have a medical condition, talk to your GP or a dietitian.