Histamine is a chemical messenger involved in immune responses, stomach acid regulation, and neurotransmission. It is stored in mast cells and basophils throughout the body and released in response to allergens, injury, and certain foods. In normal amounts, histamine is part of healthy immune function. Problems arise when histamine accumulates faster than the body can break it down, or when mast cells release it inappropriately.
Histamine intolerance is a condition where the body's capacity to metabolise histamine is reduced, usually due to low activity of diamine oxidase (DAO), the primary enzyme responsible for breaking down dietary histamine in the gut. People with histamine intolerance may experience headaches, flushing, nasal congestion, hives, digestive discomfort, and heart palpitations after consuming high-histamine foods such as aged cheeses, cured meats, fermented foods, red wine, and certain fish.
Mast cell activation syndrome (MCAS) is a separate but related condition in which mast cells release histamine and other mediators unpredictably, often without an obvious trigger. Symptoms can overlap significantly with histamine intolerance, making laboratory investigation an important part of the clinical workup.
This test measures histamine in whole blood. Because histamine is rapidly metabolised, a single blood measurement reflects histamine at the moment of collection and may not capture episodic spikes. Testing during or shortly after a symptomatic episode tends to be more informative than testing during an asymptomatic period. Sample handling also matters: histamine degrades quickly if the sample is not kept cold after collection, so letting the pathology centre know you are having a histamine test is important for accurate results.
Results are most useful when interpreted alongside DAO activity, your symptom diary, and dietary history. Your practitioner can advise on whether additional testing is appropriate for your situation.
To assess circulating histamine levels in people with suspected histamine intolerance, mast cell conditions, chronic allergic symptoms, or unexplained reactions to high-histamine foods and environmental triggers.
