What is the relationship between Small Intestine Bacterial Overgrowth (SIBO) and Histamine Intolerance?

Small intestinal bacterial overgrowth (SIBO) and histamine intolerance are often interconnected conditions that can cause overlapping digestive symptoms. SIBO occurs when excessive bacteria grow in the small intestine, while histamine intolerance happens when your body cannot properly break down histamine, a compound involved in immune responses and digestion. The connection exists because the bacterial overgrowth in SIBO can increase histamine production while simultaneously damaging the intestinal lining, which may reduce production of diamine oxidase (DAO), the enzyme that breaks down histamine. To address both conditions, a two-pronged approach is recommended. First, treat the SIBO with either prescription antibiotics like rifaximin (550mg three times daily for 14 days) or herbal antimicrobials such as oregano oil, berberine, or allicin (follow product dosing for 4-6 weeks). Second, follow a low-histamine diet temporarily (4-6 weeks) by avoiding fermented foods, aged cheeses, cured meats, alcohol, and other high-histamine foods. Supplements that may help include DAO enzymes (taken before meals containing histamine) and quercetin (500mg twice daily). Probiotics containing Bifidobacterium species rather than Lactobacillus may be beneficial as they typically produce less histamine. Once SIBO is resolved, histamine tolerance often improves as the gut lining heals and enzyme production normalizes, allowing for gradual reintroduction of histamine-containing foods.