Histamine is a chemical produced by cells in the body when experiencing an allergic reaction or infection. However, if overproduced, histamine can cause problems and interfere with some bodily functions. When you are allergic to certain substances such as dust, pollen, pet dander, or food, the immune system considers these substances harmful to the body. In order to protect the body, the immune system starts a chain reaction that makes some body cells release histamine and other chemicals into the bloodstream. Effects of Histamine in the Body In addition to helping the immune system fight infections and allergies, histamine also plays a role in supporting several bodily functions, including as a component of stomach acid which helps destroy food in the digestive process, as well as being a neurotransmitter that transmits messages from the body to the brain. Although its function is important, histamine production should not be excessive. The production of too much histamine is k...