Word parts
What it means
A group of drugs that stop histamineHIS-tuh-meenA chemical released by certain immune cells that widens blood vessels, makes them leaky and tightens airway muscles.hist/o tissue-amine a type of nitrogen-containing chemicalFull entry from acting on its H1 receptors. They ease sneezing, runny nose, itching and hives, and some are used for motion sickness or sleep. First-generation drugs such as diphenhydramine cross into the brain and cause drowsiness and dry mouth. Second-generation drugs such as loratadine and cetirizineseh-TEER-ih-zeenA second-generation antihistamine used for allergy symptoms and hives.Full entry cause much less drowsiness. Acid-reducing H2 blockers also block histamine but are a separate class.
For the nurse
Warn about drowsiness and driving with first-generation drugs. In older adults these drugs can cause confusion, constipation and urinary retention, and they are on the Beers list of drugs to avoid. They do not treat anaphylaxisan-uh-fuh-LAK-sisA sudden, severe allergic reaction that affects the whole body.ana- away, against-phylaxis protectionFull entry : epinephrine comes first.
At a glance
| Drug class | H1 receptor antagonist |
|---|---|
| Spanish | antihistamínico |
| Also written | antihistamines, H1 blocker, histamine-1 receptor antagonist |
Related terms
histamine
A chemical released by certain immune cells that widens blood vessels, makes them leaky and tightens airway muscles.
allergic reaction
A harmful response of the immune system to a substance that is harmless to most people.
anticholinergic
A drug or effect that blocks acetylcholine, a nerve messenger, in parts of the nervous system.
cetirizine
A second-generation antihistamine used for allergy symptoms and hives.