Histamine exerts its actions by combining with specific cellular histamine receptors. The four histamine receptors that have been discovered are designated H1 through H4.
| Type | Location | Function |
| H1 histamine receptor | Found on smooth muscle, endothelium, and central nervous system tissue | Causes vasodilation, bronchoconstriction, bronchial smooth muscle contraction, separation of endothelial cells (responsible for hives), and pain and itching due to insect stings; the primary receptors involved in allergic rhinitis symptoms and motion sickness. |
| H2 histamine receptor | Located on parietal cells | Primarily stimulate gastric acid secretion |
| H3 histamine receptor | Found on central nervous system and to a lesser extent peripheral nervous system tissue | Decreased neurotransmitter release: histamine, acetylcholine, norepinephrine, serotonin |
| H4 histamine receptor | Found primarily in the basophils and in the bone marrow. It is also found on thymus, small intestine, spleen, and colon. | Plays a role in chemotaxis. |
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