Diphenhydramine is a common antihistamine used by the general public to treat allergies.

Generic Name: Diphenhydramine hydrochloride
Brand Name: Benadryl
Classification: Antihistamine, second generation, ethanolamine


  1. Treatment of hypersensitivity reactions
  2. Treatment of motion sickness
  3. Treatment of Parkinsonism
  4. Nighttime sleep aid
  5. Antitussive


  1. Has high sedative, anticholinergic and antiemetic effects
  2. Blocks the action of acetylcholine
  3. Blocks H-1 receptors on effector cells of the GI tract, blood vessels, and respiratory tract


  1. Use with other products containing diphenhydramine
  2. Hypersensitivity to antihistamines

Special Concerns:

  1. Increases the risk of cognitive decline in the elderly
  2. Use with caution in clients suffering from the following: Increased Pressure in the Eye, Closed Angle Glaucoma, Chronic Difficulty having a Bowel Movement, High Blood Pressure, Stenosing Peptic Ulcer, Blockage of Urinary Bladder, Enlarged Prostate, Cannot Empty Bladder, Overactive Thyroid Gland


  1. Drowsiness
  2. Constipation
  3. Diarrhea
  4. Dizziness
  5. Dry mouth/nose/throat
  6. Headache
  7. Anorexia
  8. N&V
  9. Anxiety
  10. GI upset
  11. Asthenia


Per Orem: 25-50 mg TID- QID

IV: 10-50mg up to 100mg/IV

Nursing Considerations:

  1. Give full prophylactic dose 30min. prior to travel if used as a prophylaxis for motion sickness
  2. Take similar doses with meals and at bedtime
  3. Do not use more than 2 weeks to treat insomnia
  4. For IV, may give undiluted
  5. Do not exceed IV rate of 25mg/minute
  6. Drug causes drowsiness. Avoid activities requiring mental alertness
  7. Use sun protection as it may cause photosensitivity
  8. Use sugarless candy/gum to diminish dry mouth effects
  9. Avoid alcohol and other CNS depressants
  10. Stop therapy 72-96 hr. prior to skin testing. Report adverse effect and lack of response
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