Antihistamines
Medication class detail with safety cues and nursing action focus.
Antihistamines
Examples: diphenhydramine, loratadine, cetirizine, promethazine
Mechanism
Blocks histamine effects; first-generation agents also cause sedation and anticholinergic drying.
Used for
- Allergic rhinitis
- Urticaria or itching
- Motion sickness or nausea for selected agents
- Mild allergic reactions
Side effects
- Sedation
- Dry mouth
- Urinary retention
- Blurred vision
- Falls
Nursing actions
- Assess allergy symptoms, airway involvement, sedation level, and fall risk.
- Distinguish mild allergy support from anaphylaxis, which needs emergency treatment.
- Use caution with older adults and other CNS depressants.
Hold / question cues
- Airway swelling, wheezing, or hypotension suggesting anaphylaxis
- Severe sedation or respiratory depression with other depressants
- Acute glaucoma or urinary retention concerns for anticholinergic agents
Antidote / reversal
- No routine antihistamine antidote is seeded; treat severe toxicity supportively and follow poison-control/provider guidance.
NCLEX pearl
- First-generation antihistamines can make clients sleepy, dry, and fall-prone.
Individual drug cards
Respiratory depression with a sedating antiemetic is an airway priority.
Airway swelling is the priority, not routine antihistamine teaching.
Second-generation does not mean zero sedation risk.
Drowsiness can still occur with cetirizine.
Antihistamine sedation and anticholinergic burden are OTC source targets.
Related study cards
Shows conditions, glossary terms, Drive entities, and source-linked cards connected to this medication class.
Review Cetirizine through the Upper Respiratory Tract Disorders source folder: know why it is used, what makes it unsafe, what to assess first, and what the client must report.
Review Diphenhydramine through the Over-the-Counter Meds source folder: know why it is used, what makes it unsafe, what to assess first, and what the client must report.
Review Diphenhydramine through the Upper Respiratory Tract Disorders source folder: know why it is used, what makes it unsafe, what to assess first, and what the client must report.
Review Loratadine through the Over-the-Counter Meds source folder: know why it is used, what makes it unsafe, what to assess first, and what the client must report.
Drowsiness can still occur with cetirizine.
Airway swelling is the priority, not routine antihistamine teaching.
Antihistamine sedation and anticholinergic burden are OTC source targets.
Second-generation does not mean zero sedation risk.