Letzte Aktualisierung am 4. March 2025 von Dr. Michael Zechmann-Khreis
Step-by-step explanation
The diagnosis of histamine intolerance (HIT) is a complex process that requires a thorough examination and close cooperation between doctor and patient. The symptoms of histamine intolerance are often non-specific and can easily be confused with other illnesses, which is why a precise diagnosis is important.
Keep a symptom diary
An important first step in the diagnosis is to keep a detailed symptom diary, which should be kept for about two weeks. Make detailed notes in this diary:
- Nutrition: What did you eat and drink?
- Lifestyle: Have you done sports or other physical activities?
- Mental and physical condition: How did you feel, both mentally and physically? Were there any stress factors?
- Cycle phases: In women, the menstrual cycle should also be taken into account, as hormonal fluctuations can influence the symptoms.
- Symptoms and their chronological sequence: When did the symptoms begin and how did they develop over time?
This step helps the doctor to recognize patterns and possible connections between certain lifestyle habits and symptoms. Symptom tracking apps can also be useful here.
Exclusion procedure – investigate other diseases
One of the biggest challenges in diagnosing histamine intolerance is ruling out other possible causes for the symptoms. There are many conditions that can cause similar symptoms, including
- Allergies (e.g. pollen or food allergies)
- Mast cell activation syndrome (MCAS)
- Food intolerances such as lactose or fructose intolerance
- Gastrointestinal diseases such as irritable bowel syndrome or chronic inflammatory bowel disease (e.g. Crohn’s disease)
These conditions must be carefully investigated before a diagnosis of histamine intolerance can be made.
Blood tests – DAO activity and histamine levels
Blood tests to determine diamine oxidase (DAO) activity or histamine levels are often used to diagnose histamine intolerance, but should be used with caution. DAO is an enzyme that is responsible for the breakdown of histamine in the body. A DAO level below 10 U/mL may indicate histamine intolerance. However, DAO activity alone is not a reliable indicator. Furthermore, there is no clear correlation between DAO levels and the symptoms of histamine intolerance.
The measurement of histamine levels in the blood is also carried out, but does not provide clear results either. It is unclear whether the histamine measured in the blood comes from food or is produced by the body itself. In addition, there are no reliable studies that confirm a clear link between increased histamine levels in the blood and histamine intolerance symptoms.
Gastrointestinal symptoms after food intake and a reduced DAO level below 10 U/mL could be an indication of HIT. This could currently be the most useful diagnostic measure with regard to blood tests.
Important: Blood tests alone cannot provide a reliable diagnosis of histamine intolerance!
Elimination diet
An elimination diet is often recommended to confirm the diagnosis. During this diet, histamine-rich foods such as matured cheeses, sausages, alcoholic drinks and fermented foods are avoided for a period of 2-3 weeks. If the symptoms improve significantly during this time, this is a strong indication of histamine intolerance.
Provocation test under medical supervision
In some cases, a provocation test can be useful. This involves administering histamine-rich foods under medical supervision in order to provoke a reaction. This helps to confirm histamine sensitivity. However, such a test can trigger severe symptoms and should therefore be carried out with caution.
Other diagnostic tests
There are also other tests, such as skin tests, stool tests or urine tests, but these do not provide reliable results. The histamine content in the urine can be increased by a high-protein diet, and the histamine content in the stool is not conclusive, as bacteria in the intestine can also produce histamine. In addition, it is not possible to reliably determine whether orally ingested histamine leads to symptoms in the intestine or is simply excreted.
Alternative methods such as TCM tests, laying on of hands, pendulum, hair analysis and the like are of course not valid methods either.
The diagnosis of histamine intolerance requires a comprehensive examination and close observation of the symptoms. In addition to the medical history, documentation of symptoms and the exclusion procedure, a combination of blood tests and an elimination diet is important. As the symptoms of histamine intolerance can be very varied and non-specific, diagnosis often remains a challenge. It is important that the diagnostic process is carried out together with an experienced doctor in order to obtain a clear and well-founded diagnosis. A blood test alone is not enough to make a diagnosis.
Sources
Arih, K., Đorđević, N., Košnik, M., & Rijavec, M. (2023). Evaluation of Serum Diamine Oxidase as a Diagnostic Test for Histamine Intolerance. Nutrients, 15(19), 4246. https://doi.org/10.3390/nu15194246
Bent, R. K., Kugler, C., Faihs, V., Darsow, U., Biedermann, T., & Brockow, K. (2023). Placebo-Controlled Histamine Challenge Disproves Suspicion of Histamine Intolerance. The Journal of Allergy and Clinical Immunology: In Practice, 11(12), 3724-3731.e11. https://doi.org/10.1016/j.jaip.2023.08.030
Giera, B., Straube, S., Konturek, P., Hahn, E. G., & Raithel, M. (2008). Plasma histamine levels and symptoms in double blind placebo controlled histamine provocation. Inflammation Research, 57(S1), 73-74. https://doi.org/10.1007/s00011-007-0636-9
Jarisch, R. (ed.). (2022). Histamine intolerance: causes, symptoms, treatment: everything for a symptom-free life (1st edition). TRIAS.
Reese, I., Ballmer-Weber, B., Beyer, K., Dölle-Bierke, S., Kleine-Tebbe, J., Klimek, L., Lämmel, S., Lepp, U., Saloga, J., Schäfer, C., Szépfalusi, Z., Treudler, R., Werfel, T., Zuberbier, T., & Worm, M. (2021). Guideline on the procedure for suspected intolerance to orally ingested histamine. Allergology, 44(10), 761-772. https://doi.org/10.5414/ALX02269
