diphenhydramine, Benadryl (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

SIDE EFFECTS: Diphenhydramine commonly can cause:

  • sedation,
  • tiredness,
  • sleepiness,
  • dizziness,
  • disturbed coordination,
  • drying and thickening of oral and other respiratory secretions, and
  • urinary retention.

Diphenhydramine also may cause

Diphenhydramine should be used with caution (if at all) in persons with narrow-angle glaucoma, prostatic hypertrophy (enlarged prostate gland), hyperthyroidism, cardiovascular disease, high blood pressure (hypertension), and asthma.

GENERIC AVAILABLE: Yes

PRESCRIPTION: No. Yes (Injection)

PREPARATIONS:

  • Capsules: 25 and 50 mg. Tablets: 12.5, 25 and 50 mg.
  • Tablet (Chewable or dispersible)): 12.5 mg.
  • Strips: 12.5 and 25 mg.
  • Elixir, oral solution, liquid: 12.5 mg per teaspoon (5 mL).
  • Strip: 25 mg. Injection: 50 mg per ml.

STORAGE: Diphenhydramine should be stored at room temperature, 15 C to 30 C (59 F to 86 F), and the injection should be protected from freezing and light.

DOSING: Diphenhydramine doses vary depending on formulation, and has its maximal effect about one hour after it is taken.

  • When used to treat insomnia, it is prescribed at bedtime. Indivduals over the age of 60 years are especially sensitive to the sedating and anticholinergic effects of diphenhydramine, and the dose should be reduced.
  • A common regimen for treating adult allergic reaction is 25-50 mg every 4-6 hours not to exceed 300 mg daily.
  • Insomnia is treated with 50 mg taken 30 minutes before bedtime.
Medically Reviewed by a Doctor on 3/27/2015


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