Histamine
What it isEndogenous amine acting at H1 to H4 receptors, mediating arousal, allergy and gastric acid.
Why this oneThe whole antihistamine and H2 blocker landscape is defined by which receptor is engaged and whether the drug enters the brain.
What limits itH1 blockade in the CNS causes sedation; peripherally restricted antihistamines exist precisely to avoid it.
NO BOXED WARNINGS
Principal riskEndogenous or dietary; no boxed warning applies
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilitySystemic vasodilation and bronchoconstriction with excessive diagnostic exposure