Summary: Histamine is naturally found in the human body. It acts as a mediator of inflammatory processes, and allergic reactions. Moreover, it is a neurotransmitter that stimulates the secretion of gastric acid. It is also found in many food products we, mainly in highly processed products with the use of fermentation. Histamine intolerance (HIT) is a non-immunological pathology. It is defined as an imbalance between the histamine accumulated in the body and the ability to degrade it. Histamine intolerance in children can be either primary (genetic) or secondary – caused by, for example, another disease, ingested food or drugs. Gastrointestinal symptoms (chronic, diffuse abdominal pain, diarrhoea, vomiting and flatulence) seem to be most common among paediatric patients with HIT. So far, no unequivocal algorithm for histamine intolerance diagnosis in children has been developed. Based on the data from the literature, a possible diagnostic scheme in children with suspicion of histamine intolerance is proposed in this paper. Available treatment methods are also discussed.