Banophen (Diphenhydramine) Dosing for Allergic Symptoms
For adults and children over 12 years, administer 25-50 mg orally every 4-6 hours, not exceeding 6 doses in 24 hours; for children 6 to under 12 years, give 25 mg (10 mL) every 4-6 hours; diphenhydramine is not recommended for children under 6 years of age for over-the-counter use. 1
Adult Dosing
- Oral administration: 25-50 mg every 4-6 hours as needed, with a maximum of 6 doses per 24-hour period 1
- Intravenous administration: 25-50 mg when used as an adjunct in medical procedures, with onset of action within several minutes and duration of 4-6 hours 2
- The drug distributes quickly throughout the body, including the central nervous system 2
Pediatric Dosing
- Children 6 to under 12 years: 25 mg (10 mL of oral solution) every 4-6 hours, not exceeding 6 doses in 24 hours 1
- Children under 6 years: Do not use for over-the-counter allergic symptom relief 1
- For prevention of drug-induced akathisia in children: 1-2 mg/kg per dose (maximum 50 mg) administered parenterally 3
Important Clinical Considerations
Pharmacokinetics
- Onset of action occurs within several minutes when given intravenously 2
- Duration of effect is 4-6 hours 2
- The sedative effect is enhanced when combined with alcohol or other CNS depressants such as benzodiazepines or opioid narcotics 2
Common Adverse Effects
- Hypotension, dizziness, blurred vision, dry mouth, epigastric discomfort, urinary retention, and wheezing 2
- Sedation and cognitive/psychomotor impairment are recognized side effects that may decrease awareness of symptoms 2
- Excessive sedation can occur, particularly when combined with other sedating medications 3
Critical Safety Warnings
Toxicity Thresholds
- Children under 6 years: Ingestions of ≥7.5 mg/kg require emergency department evaluation 4
- Patients 6 years and older: Ingestions of ≥7.5 mg/kg or 300 mg (whichever is less) require emergency department evaluation 4
- Toxic doses can cause loss of consciousness, seizures, QRS widening, agitation, hallucinations, and respiratory depression 4
Special Precautions
- Topical diphenhydramine can be absorbed systemically and has resulted in fatal toxicity in children 5
- Rapid intravenous administration or excessive doses can cause clinically significant and potentially life-threatening adverse effects 6
- Monitor for dystonic reactions when used with medications like prochlorperazine or metoclopramide 2
Role in Anaphylaxis Management
- Diphenhydramine is considered adjunctive therapy only for anaphylaxis and should never substitute for epinephrine 2
- Useful only for relieving itching and urticaria; does not relieve stridor, shortness of breath, wheezing, gastrointestinal symptoms, or shock 2
- First-generation H1 antihistamines like diphenhydramine 25-50 mg can be given orally or intravenously as adjunctive treatment 2
- Alternative dosing with less-sedating second-generation antihistamines (such as cetirizine 10 mg) may be preferred due to faster onset and reduced sedation 2