Wiktionary
histaminergic
a. Of or pertaining to the effects of histamine at a receptor in an affected tissue
Wikipedia
Histaminergic
Histaminergic means "working on the histamine system", and histaminic means "related to histamine".
A histaminergic agent (or drug) is a chemical which functions to directly modulate the histamine system in the body or brain. Examples include histamine receptor agonists and histamine receptor antagonists (or antihistamines). Subdivisions of histamine antagonists include H receptor antagonists, H receptor antagonists, and H receptor antagonists.