From the Guidelines
The recommended intravenous (IV) dose of Diphenhydramine (Benadryl) for adults is typically 25-50 mg administered slowly over 2-5 minutes, with a maximum single dose of 50 mg, as stated in the study by 1 and 1.
Key Considerations
- For children, the IV dose is 1-2 mg/kg/dose up to a maximum of 50 mg per dose.
- Benadryl should be administered slowly when given IV to avoid hypotension and other adverse effects.
- The medication can be repeated every 4-6 hours as needed, with a maximum daily dose of 400 mg for adults.
Administration and Monitoring
- When administering IV Benadryl, patients should be monitored for common side effects including sedation, dizziness, and anticholinergic effects like dry mouth and blurred vision.
- IV Benadryl works more rapidly than oral formulations, making it useful for urgent treatment of allergic reactions, although epinephrine remains the first-line treatment for anaphylaxis.
- The medication works by blocking histamine H1 receptors, thereby reducing allergic symptoms like itching, swelling, and hives.
Special Considerations
- Caution should be used in elderly patients and those with certain conditions like glaucoma, prostatic hypertrophy, or cardiovascular disease.
- It is essential to note that H1 antihistamines like diphenhydramine are considered second-line therapy to epinephrine and should never be administered alone in the treatment of anaphylaxis, as emphasized in the study by 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION: ... Pediatric Patients, other than premature infants and neonates: 5 mg/kg/24 hr or 150 mg/m 2/24 hr. Maximum daily dosage is 300 mg. Divide into four doses, administered intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly Adults: 10 to 50 mg intravenously at a rate generally not exceeding 25 mg/min, or deep intramuscularly, 100 mg if required; maximum daily dosage is 400 mg.
The dose of Diphenhydramine (Benadryl) for intravenous (IV) administration is:
- For pediatric patients (other than premature infants and neonates):
- 5 mg/kg/24 hr or 150 mg/m 2/24 hr,
- maximum daily dosage is 300 mg,
- divide into four doses,
- administered at a rate generally not exceeding 25 mg/min.
- For adults:
- 10 to 50 mg,
- administered at a rate generally not exceeding 25 mg/min,
- maximum daily dosage is 400 mg 2.
From the Research
Dose of Diphenhydramine for IV Administration
- The dose of Diphenhydramine (Benadryl) for intravenous (IV) administration is not consistently reported across studies, but specific instances are mentioned:
- It's essential to note that the appropriate dose may vary based on the specific medical condition being treated, patient age, and other factors.
Administration and Effects
- Diphenhydramine can be administered orally, intramuscularly, or intravenously, with different onset times for each route 5.
- The drug has various effects, including sedation, impairment of psychomotor performance, and cognitive function, which should be considered when choosing a treatment option 6, 7.