This group includes histamine and betahistine. For medical use of histamine is produced by bacterial breakdown of histidine or synthetically. Histamine is injected parenterally, because if ingested, it is poorly absorbed and has low efficiency. Wide application as a drug histamine is not.

Sometimes histamine is used with polyarthritis, articular and muscular rheumatism: the intradermal injection of histamine dihydrochloride (0,1–0,5 ml 1% solution), rubbing ointments containing histamine, and electrophoresis histamine cause severe hyperemia and reducing pain. The pain associated with the nerves (radiculitis, plexitis, etc.), it is with the same purpose, is injected intradermally (0.2–0.3 ml of 0.1% solution).

In allergic diseases, including bronchial asthma, urticaria, etc., as well as migraines, perhaps a course of desensitization small, increasing doses of histamine. At the same time developing resistance to histamine and reduced predisposition to allergic reactions.

Histamine is also used for pharmacological diagnosis of pheochromocytoma, functional state of the stomach. It is necessary to take great precautions because of possible side effects (hypotensive effect, bronchospasm, etc.).

In overdose and increased sensitivity to histamine may develop collapse and shock.

Betahistin is diaminoksidazy inhibitor — enzyme inactivating histamine. It stabilizes endogenous histamine and has gistaminopodobnoe action. Betagistin effective when administered orally, it relaxes the precapillary sphincters of the vessels of the inner ear, improves microcirculation. It is used for Meniere's disease and other diseases characterized by attacks of vertigo, tinnitus, hearing loss, etc.