| Question |
Answer |
| GENERIC NAME | Diphenhydramine |
| BRAND NAME | Benadryl |
| CLASS | Antihistamine,anticholinergic |
| MECHANISM OF ACTION | Blocks cellular histamine receptors; decreases vasodilation; decreases motion sickness. Reverses extrapyramidal reactions. |
| INDICATIONS | Symptomatic relief of allergies, allergic reactions, anaphylaxis, acute dystonic reactions (phenothiazines). Blood administration reactions; used for motion sickness, hay fever. |
| CONTRAINDICATIONS | Asthma, glaucoma, pregnancy, hypertension, narrow angle glaucoma, infants, patients taking monoamine oxidase inhibitors (MAOIs) |
| ADVERSE REACTIONS | Sedation. Hypotension, seizures, visual disturbances, vomiting, urinary retention, palpitations, arrhythmias, dry mouth and throat, and paradoxical CNS excitation in children. |
| NOTES ON ADMINISTRATION | Not used in infants or in pregnancy; Category B. If used in anaphylaxis, will be in conjunction with epinephrine, corticosteroids. |
| INCOMPATABILITIES/DRUG INTERACTIONS | Potentiates effects of alcohol, and other anticholinergics, may inhibit corticosteroid activity; MAOIs prolong anticholinergic effects of Diphenhydramine. |
| DOSE/ROUTE;Adult | 25-50mg IV, IM, or PO. |
| DOSE/ROUTE;Pediatric | 1-2 mg/kg IV. IO slowly, or IM. If given PO;5mg/kg/24 hours |
| ONSET OF ACTION | 15-30 minutes |
| PEAK EFFECTS | 1 hour |
| DURATION OF ACTION | 3-12 hours. |
| AZ DRUG BOX SUPPLY RANGE | 50 mg. |
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