Diphenhydramine (Benadryl)

ATI-format individual drug card with NCLEX-focused assessment, safety, teaching, and source attribution.

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Diphenhydramine (Benadryl)

ATI class: Antihistamine / First-generation H1 receptor antagonist

Action

  • Blocks H1 histamine receptors.
  • Has anticholinergic and sedating effects.

Therapeutic use

  • Allergic rhinitis
  • Urticaria or itching
  • Motion sickness
  • Short-term insomnia support when ordered

Nursing assessment

  • Assess airway involvement before treating allergy symptoms as routine.
  • Monitor sedation, respiratory status, fall risk, and anticholinergic effects.
  • Screen older adults for confusion, urinary retention, constipation, and glaucoma risk.

Administration

  • PO
  • IV
  • IM
  • Topical

Side effects

  • Drowsiness
  • Dry mouth
  • Blurred vision
  • Constipation
  • Dizziness

Adverse effects

  • Respiratory depression with other sedatives
  • Paradoxical excitation
  • Urinary retention
  • Confusion or delirium

Interactions

  • Alcohol
  • Opioids
  • Sedative-hypnotics
  • Other anticholinergics
  • MAOIs

Contraindications

  • Hypersensitivity
  • Newborn or premature infant use unless specifically directed

Precautions

  • Use caution with older adults, glaucoma, BPH, urinary retention, asthma/COPD, and fall risk.
  • Avoid duplicate OTC sleep, allergy, and cold products that contain diphenhydramine.

Client teaching

  • Avoid alcohol, driving, and hazardous activity until response is known.
  • Report trouble breathing, severe confusion, inability to urinate, or worsening symptoms.
  • Check OTC labels to avoid duplicate diphenhydramine dosing.

Medication outcomes

  • Decreased itching, sneezing, runny nose, or hives
  • Improved motion-sickness symptoms when used appropriately

Antidote / rescue

  • No routine antidote is seeded; severe anticholinergic toxicity requires urgent provider or poison-control guidance.

NCLEX priority cues

  • Airway swelling is the priority, not routine antihistamine teaching.
  • Older adult confusion, urinary retention, or falls are safety red flags.
  • Duplicate OTC diphenhydramine is a common hidden-risk question.

Medication classes

Antihistamines

Source attribution

Engage_MedTable_Diphenhydramine (3).pdf
ati-pdf
Google Drive source topic: Over-the-counter meds / Upper respiratory
google-drive
Sentinel pharmacology API reference
sentinel-api
Manual ATI-format NCLEX normalization
manual-seed

Related study cards

Shows the medication class, ATI cues, source references, and connected study cards for this drug.

12 study links
Med classmedication class
Antihistamines

Blocks histamine effects; first-generation agents also cause sedation and anticholinergic drying.

ATI cueNCLEX Priority Cue
Airway swelling is the priority, not routine antihistamine teaching.

ATI medication nclex priority cue concept.

ATI cueInteraction
Alcohol

ATI medication interaction concept.

ATI cueTherapeutic Use
Allergic rhinitis

ATI medication therapeutic use concept.

ATI cueClass
Antihistamine

ATI medication class concept.

ATI cueNursing Assessment
Assess airway involvement before treating allergy symptoms as routine.

ATI medication nursing assessment concept.

ATI cueClient Teaching
Avoid alcohol, driving, and hazardous activity until response is known.

ATI medication client teaching concept.

ATI cuePrecaution
Avoid duplicate OTC sleep, allergy, and cold products that contain diphenhydramine.

ATI medication precaution concept.

ATI cueMechanism of Action
Blocks H1 histamine receptors.

ATI medication mechanism of action concept.

ATI cueSide Effect
Blurred vision

ATI medication side effect concept.

ATI cueClient Teaching
Check OTC labels to avoid duplicate diphenhydramine dosing.

ATI medication client teaching concept.

ATI cueAdverse Effect
Confusion or delirium

ATI medication adverse effect concept.