Histamine intolerance is a condition where your body has high levels of histamine and cannot break it down properly1. Histamine is a chemical responsible for several major functions, including sending messages to your brain, triggering the release of stomach acid to help digestion, and releasing after injury or allergic reaction as part of your immune response.

When there’s too much histamine, your body can’t break it down properly, leading to histamine intolerance1. This condition can affect multiple systems in your body, but gastrointestinal symptoms are most common.

Symptoms of histamine intolerance can vary from person to person and may include digestive issues, abdominal pain, bloating, diarrhea, constipation, flatulence, nausea, vomiting, headaches or migraines, nasal congestion or sinus issues, fatigue, itchy skin, hives, irregular menstrual cycle, and in more severe cases, abdominal cramping, tissue swelling, high blood pressure, irregular heart rate, anxiety, difficulty regulating body temperature, and dizziness.

Histamine intolerance is caused by a deficiency in the enzyme diamine oxidase (DAO), which is responsible for breaking down histamine that you take in from foods1. Factors that can affect your DAO enzyme or histamine levels include genetics, certain medications, and gastrointestinal disorders.

Please note that while histamine intolerance can cause symptoms similar to an allergic reaction, it is not an allergy2. It’s sometimes referred to as a “pseudoallergy” since it looks similar to an allergy but has a different cause2. It’s estimated that about 1 in 100 people have histamine intolerance, but it can be hard to diagnose due to its nonspecific symptoms.

If you suspect you have histamine intolerance, it’s important to consult with a healthcare professional for a proper diagnosis and treatment plan. Treatment often involves a low-histamine diet and possibly medication to help manage symptoms.