Frequent headaches, flushing, digestive upset, or allergy-like symptoms without a clear cause may point to histamine intolerance. Histamine is a natural compound involved in immunity, digestion, and nerve signaling. It’s found in certain foods and produced by the body, then broken down by enzymes like DAO and HNMT. When histamine builds up faster than it’s cleared, symptoms occur. Common signs include headaches, rashes, nasal congestion, bloating, diarrhea, and anxiety. Causes may include low DAO activity, gut imbalances (like SIBO), mold exposure, or high-histamine foods such as aged cheeses, fermented products, alcohol, and processed meats. Identifying triggers and supporting healthy histamine metabolism—often with diet and gut support—can bring significant relief.