Histamine is an endogenous, short-acting biogenic amine synthesized from the amino acid histidine and widely found throughout the body. It is stored in the granules of basophils and mast cells and is an essential mediator of direct allergic reactions. Although there is usually minimal histamine in the bloodstream, increased histamine levels in plasma and tissues occur during anaphylaxis and allergic skin and airway reactions.
Histamine is also part of a class of neurotransmitters called low-molecular-weight neurotransmitters, which include serotonin, epinephrine, and dopamine.
In addition, histamine plays a role in gastric acid secretion in the stomach by inducing its production.
