Diphenhydramine (Benadryl) IVP Dosing Frequency
For adults, diphenhydramine can be administered intravenously at 25-50 mg per dose, with a maximum daily dosage of 400 mg, divided into multiple doses as needed. 1
Adult Dosing
- Standard IV dose: 25-50 mg per dose administered at a rate not exceeding 25 mg/minute 1
- Maximum daily dosage: 400 mg 1
- For acute hypersensitivity reactions: 25-50 mg administered parenterally (IV push) 2
- For treatment of dystonic reactions: 25-50 mg IV 2
Pediatric Dosing
- 1-2 mg/kg/dose or 5 mg/kg/24 hours divided into four doses 1
- Maximum daily dosage: 300 mg 1
- Administration rate should generally not exceed 25 mg/minute 1
- For acute hypersensitivity reactions: 1-2 mg/kg per dose 2
Administration Considerations
- IV administration should be slow, generally not exceeding 25 mg/minute to minimize adverse effects 1
- When administering via IVP, monitor for cardiovascular effects including hypotension and cardiac arrhythmias 3
- Rapid IV administration may precipitate seizures in some patients 2
Clinical Cautions
- Diphenhydramine can cause sedation and respiratory suppression, especially when combined with other sedative agents 2
- In patients with allergic reactions, diphenhydramine should be considered second-line therapy to epinephrine and should never be administered alone in the treatment of anaphylaxis 2
- Cardiac monitoring is recommended during IV administration, particularly in patients with cardiovascular disease 3
- A case report documented cardiac arrest in an infant with congenital heart disease following IV diphenhydramine administration, highlighting the need for caution in vulnerable populations 3
Special Populations
- For elderly patients, consider using lower doses due to increased sensitivity to anticholinergic effects and greater risk of adverse reactions 1
- In patients with hepatic impairment, dose reduction may be necessary due to decreased drug metabolism 1
Common Pitfalls
- Administering too rapidly (faster than 25 mg/minute), which increases risk of hypotension and arrhythmias 1
- Exceeding maximum daily dose recommendations (400 mg for adults, 300 mg for children) 1
- Using diphenhydramine as first-line treatment for anaphylaxis instead of epinephrine 2
- Failing to monitor patients for respiratory depression, especially when combined with other sedatives 2
Remember that diphenhydramine should be individualized according to patient needs and response, with careful monitoring for adverse effects, particularly when administered intravenously 1.