Diphenhydramine (Benadryl, Various)


  • Miscellaneous


  • Antihistimine, antivertigo agent, antipruritic, hypnotic


  • Perenial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis

  • Pruritic conditions, mild urticaria and angioedema, motion sickness

  • Sleep aid, cough suppressant, adjuntive therapy for anaphylactic reactions


  • Narrow-angle glaucoma

  • Bladder neck obstruction


  • Pregnancy category C; contraindicated for nursing infants

  • Avoid use of alcohol or other CNS depressants while taking drug

  • Avoid driving or other hazardous activities if drowsiness occurs

Adverse Reactions (Side Effects):

  • CNS: anxiety, confusion, dizziness, drowsiness, euphoria, fatigue, neuritis

  • CV: palpitations, tachycardia

  • EENT: blurred vision, dilated pupils, dry nose, dry throat, nasal stuffiness, tinnitis

  • GU: dysuria, frequency, impotence, retention

  • HEME: bone marrow suppression, hemolytic anemia


Administered orally (capsule, caplet, elixir), intramuscularly, intravenously

  • Adult:            

    • PO/IM/IV 

      • 15-50mg every 4 hours

      • do not exceed 400mg daily

      • for sleep PO 50mg at bedtime

  • Child:            

    • PO/IM/IV 5 mg/kg/day or 150mg per meter square per day divided every 6-8 hours

    • do not exceed 300mg daily

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